US 6,308,612 B1 · Hydraulic leveling control system for a loader type vehicle

Abstract

A control system for a lift boom pivotable with respect to a vehicle by a boom cylinder and material handling unit pivotable with respect to the boom by a unit cylinder when the control of a boom control valve and a unit control valve. The control system includes a flow divider/combiner valve and operative in a boom-raise, unit-leveling mode to pass a preset portion of the fluid displaced from the rod end of the boom cylinder to the base end of the unit cylinder. The flow divider-combiner valve is operative in a boom-lower, unit-leveling mode, to combine the fluid stream displaced from the base end unit cylinder in a preset ratio with pressurized fluid, and pass the combined stream to the rod end of the boom cylinder. The control system can be disengaged from the automatic leveling mode to enable the boom unit to be operated manually under the control of the boom and unit control valves.

Claims24

Dependent claims

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage and a first and second secondary passages and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
and
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered.

12 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
and
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve,
(f) the flow divider/combiner valve including means for adjusting said preset ratio.

13 more elements

A hydraulic control system for raising and lowering a lift boom pivotable with respect to a frame by a boom cylinder and for controlling leveling of a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom direction-control valve having first and second boom control ports, the boom direction-control valve being selectively movable from a neutral position to a boom-raise position passing fluid from a pressurized source to the first boom control port, and to a boom-lower position passing fluid from the pressure source to the second boom control port,
(b) a unit direction-control valve having first and second unit control ports, the unit direction-control valve being selectively movable from neutral position to a tilt-up position passing fluid from the pressure source to the first unit control port and to a tilt-down position passing fluid from the pressure source to the second unit control port,
(c) a proportional flow divider/combiner valve having a primary passage and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit direction-control valve is in the neutral position and the boom direction-control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the first boom control port to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the second boom control port, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised;
(e) the hydraulic circuit being configured to provide passage means when the unit direction-control valve is in the neutral position and the boom direction-control valve is in the boom-lower position:
(i) for passing fluid from the second boom control port to the tilt-up chamber of the unit cylinder and to second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passage hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder, and
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the first boom control port to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered.

11 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage, and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-down position:
(i) for passing hydraulic fluid from the fluid pressure inlet in the unit control valve to the tilt-down chamber of the unit cylinder;
(ii) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(g) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-up position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the unit control valve to the tilt-up chamber of the unit cylinder;
and
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(h) the flow divider/combiner valve including means for adjusting said preset ratio.

19 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage, and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-down position:
(i) for passing hydraulic fluid from the fluid pressure inlet in the unit control valve to the tilt-down chamber of the unit cylinder;
(ii) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(g) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-up position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the unit control valve to the tilt-up chamber of the unit cylinder;
and
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(h) means operative when the unit control valve is moved from its neutral position to either tilt-up position or the tilt-down position:
(i) to block flow between the tilt-up chamber of the unit cylinder and the second secondary passage of the flow divider/combiner valve;
and
(ii) to block flow between the tilt-down chamber of the unit cylinder and the first secondary passage of the flow divider/combiner valve.

22 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage, and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-down position:
(i) for passing hydraulic fluid from the fluid pressure inlet in the unit control valve to the tilt-down chamber of the unit cylinder;
(ii) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(g) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-up position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the unit control valve to the tilt-up chamber of the unit cylinder;
and
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(h) means operative when the unit control valve is moved from its neutral position to either tilt-up position or the tilt-down position:
(i) to block flow between the tilt-up chamber of the unit cylinder and the second secondary passage of the flow divider/combiner valve;
(ii) to block flow between the tilt-down chamber of the unit cylinder and the first secondary passage of the flow divider/combiner valve;
and
(iii) to provide passage means for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-lower chamber of the boom cylinder when the boom control valve is in the boom-lower position, and for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the fluid outlet of the boom control valve when boom control valve is in the boom-raise position.

23 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having the tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage, and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-down position:
(i) for passing hydraulic fluid from the fluid pressure inlet in the unit control valve to the tilt-down chamber of the unit cylinder;
(ii) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(g) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-up position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the unit control valve to the tilt-up chamber of the unit cylinder;
and
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(h) the hydraulic circuit including electro-responsive valve means operative when actuated:
(i) to block flow from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(ii) to block flow from the tilt-up chamber of the unit cylinder to the second secondary passage of the flow divider/combiner valve;
and
(iii) to communicate the first secondary passage with the second secondary passage of the flow divider/combiner valve, and
switch means for actuating said electro-responsive valve means.

24 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage, and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-down position:
(i) for passing hydraulic fluid from the fluid pressure inlet in the unit control valve to the tilt-down chamber of the unit cylinder;
(ii) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(g) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-up position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the unit control valve to the tilt-up chamber of the unit cylinder;
and
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the fluid outlet of the unit control valve, to tilt the unit downwardly relative to the boom,
(h) the hydraulic circuit including a two-position valve means movable between open and closed positions, the valve means being operative in the closed position:
(i) to block flow from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(ii) to block flow from the tilt-up chamber of the unit cylinder to the second secondary passage of the flow divider/combiner valve;
and
(iii) to communicate the first secondary passage with the second secondary passage of the flow divider/combiner valve, and means for moving the two-position valve means between the open and closed positions.

23 more elements

A control system for a lift boom pivotable with respect to a frame by a boom cylinder and a material handling unit pivotable with respect to the boom by a unit cylinder, the boom cylinder having a boom-raise chamber and a boom-lower chamber, the unit cylinder having a tilt-up chamber and a tilt-down chamber, the control system comprising:

(a) a boom control valve having a fluid pressure inlet and a fluid outlet, the boom control valve being movable from a neutral position to a boom-raise position and to a boom-lower position,
(b) a unit control valve having a fluid pressure inlet and a fluid outlet, the unit control valve being movable from a neutral position to a tilt-up position and to a tilt-down position,
(c) a proportional flow divider/combiner valve having a primary passage, and a first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve:
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the fluid outlet of the boom control valve, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised,
(e) the hydraulic circuit being configured to provide passage means when the unit control valve is in the neutral position and the boom control valve is in the boom-lower position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the boom control valve to the tilt-up chamber of the unit cylinder and to the second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder;
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the fluid outlet of the boom control valve;
to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered
(f) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-down position:
(i) for passing hydraulic fluid from the fluid pressure inlet in the unit control valve to the tilt-down chamber of the unit cylinder;
(ii) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder to the fluid outlet of the unit control valve;
to tilt the unit downwardly relative to the boom;
(g) the hydraulic circuit being configured to provide passage means when the unit control valve is in the tilt-up position:
(i) for passing hydraulic fluid from the fluid pressure inlet of the unit control valve to the tilt-up chamber of the unit cylinder;
and
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the fluid outlet of the unit control valve,
to tilt the unit downwardly relative to the boom.

21 more elements

(a) a boom direction-control valve having first and second boom control ports, the boom direction-control valve being selectively movable from a neutral position to a boom-raise position passing fluid from a pressurized source to the first boom control port, and to a boom-lower position passing fluid from the pressure source to the second boom control port,
(b) a unit direction-control valve having first and second unit control ports, the unit direction-control valve being selectively movable from neutral position to a tilt-up position passing fluid from the pressure source to the first unit control port and to a tilt-down position passing fluid from the pressure source to the second unit control port,
(c) a proportional flow divider/combiner valve having a primary passage and first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit direction-control valve is in the neutral position and the boom direction-control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the first boom control port to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the second boom control port, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised;
(e) the hydraulic circuit being configured to provide passage means when the unit direction-control valve is in the neutral position and the boom direction-control valve is in the boom-lower position:
(i) for passing fluid from the second boom control port to the tilt-up chamber of the unit cylinder and to second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder, and
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the first boom control port to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit including a leveling disengagement valve means movable between open and closed positions, and means for moving the disengagement valve means between said open and closed positions, the leveling disengagement valve being operative in the closed position:
(i) to block flow from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve and;
(ii) to block flow from the tilt-up chamber of the unit cylinder to the second secondary passage of the flow divider/combiner valve and;
(iii) to communicate the first secondary passage with the second secondary passage of the flow divider/combiner valve.

15 more elements

(a) a boom direction-control valve having first and second boom control ports, the boom direction-control valve being selectively movable from a neutral position to a boom-raise position passing fluid from a pressurized source to the first boom control port, and to a boom-lower position passing fluid from the pressure source to the second boom control port,
(b) a unit direction-control valve having first and second unit control ports, the unit direction-control valve being selectively movable from neutral position to a tilt-up position passing fluid from the pressure source to the first unit control port and to a tilt-down position passing fluid from the pressure source to the second unit control port,
(c) a proportional flow divider/combiner valve having a primary passage and first secondary passage and a second secondary passage, the flow divider/combiner valve being configured to divide a single inlet stream from the primary passage in a preset ratio into two separate outlet streams at the first and second secondary passages and, reversely, to combine two separate inlet streams from the first and second secondary passages in said preset ratio into a single outlet stream at the primary passage,
(d) an hydraulic circuit configured to provide passage means when the unit direction-control valve is in the neutral position and the boom direction-control valve is in the boom-raise position:
(i) for passing hydraulic fluid from the first boom control port to the boom-raise chamber of the boom cylinder;
(ii) for passing hydraulic fluid from the boom-lower chamber of the boom cylinder to the primary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the first secondary passage of the flow divider/combiner valve to the tilt-down chamber of the unit cylinder;
and
(iv) for passing hydraulic fluid from the tilt-up chamber of the unit cylinder and from the second secondary passage of the flow divider/combiner valve to the second boom control port, to maintain the unit in a preset orientation with respect to a reference plane as the boom is raised;
(e) the hydraulic circuit being configured to provide passage means when the unit direction-control valve is in the neutral position and the boom direction-control valve is in the boom-lower position:
(i) for passing fluid from the second boom control port to the tilt-up chamber of the unit cylinder and to second secondary passage of the flow divider/combiner valve;
(ii) for passing hydraulic fluid from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve;
(iii) for passing hydraulic fluid from the primary passage of the flow divider/combiner valve to the boom-lower chamber of the boom cylinder, and
(iv) for passing hydraulic fluid from the boom-raise chamber of the boom cylinder to the first boom control port to maintain the unit in a preset orientation with respect to a reference plane as the boom is lowered,
(f) the hydraulic circuit including a leveling disengagement valve means movable between open and closed positions, and means for moving the disengagement valve means between said open and closed positions, the leveling disengagement valve being operative in the closed position:
(i) to block flow from the tilt-down chamber of the unit cylinder to the first secondary passage of the flow divider/combiner valve and;
(ii) to block flow from the tilt-up chamber of the unit cylinder to the second secondary passage of the flow divider/combiner valve and;
(iii) to communicate the first secondary passage with the second secondary passage of the flow divider/combiner valve,
(g) the hydraulic circuit including passage means operative when the leveling disengagement valve means is in the closed position, to provide passage means for passing fluid between the first unit control port and the tilt-down chamber of the unit cylinder and for passing fluid between the second unit control port and the tilt-up chamber of the unit cylinder.

16 more elements

Dependencies are inferred from the claim text.

Hydraulic leveling control system for a loader type vehicle

Life of this patent

Hydraulic leveling control system for a loader type vehicle

Life of this patent

Abstract

Claims24