US 4,411,345 A · Clutch modulating system

Abstract

In an agricultural vehicle in which a power takeoff modulating valve is shifted in response to a control lever so as to pass pressurized hydraulic fluid through a groove in the outer surface thereof between recesses in an adjacent bore wall for application to a power takeoff clutch to cause engagement of the clutch, application of the hydraulic fluid pressure to the clutch is modulated by an arrangement which selectively diverts the pressurized hydraulic fluid away from the clutch and to a sump in accordance with the rate of pressure increase of the hydraulic fluid to prevent excessively rapid engagement of the clutch. The hydraulic fluid is sumped by a trimmer valve having a first end which immediately responds to high fluid pressures by sliding into a position which sumps the conduit supplying hydraulic fluid to the clutch by an amount directly related to the pressure. An opposite second end of the trimmer valve also responds to the pressure of the hydraulic fluid but much more slowly because of a restriction in the conduit coupling the second end to the hydraulic fluid supply conduit. As sufficient hydraulic fluid passes through the restriction so as to equalize the fluid pressure at the opposite ends of the trimmer valve, the trimmer valve is returned to a position in which the sump is cut off and the hydraulic fluid pressure is applied to the power takeoff clutch.

Claims11

Dependent claims

A system for modulating the application of fluid pressure to a clutch from a source of pressurized fluid comprising the combination of:

a source of pressurized fluid;
a first conduit coupled to a clutch;
a control;
means responsive to actuation of the control for coupling the source to the first conduit by a variable amount dependent on the position of the control;
a sump for pressurized fluid;
a second conduit coupled to the first conduit;
and
means for coupling the second conduit to the sump to an extent directly related to the rate of pressure increase of fluid in the second conduit.

5 more elements

A power takeoff clutch modulating system comprising:

a power takeoff control lever;
a power takeoff modulating valve mounted within a bore and slidable in response to movement of the power takeoff control lever;
a source of pressurized hydraulic fluid;
a first recess in the bore coupled to the source of pressurized hydraulic fluid;
a second recess in the bore located adjacent and spaced apart from the first recess;
a groove in the modulating valve adapted to couple the first recess to the second recess by increasingly greater amounts as the control lever is moved from a disengage position into an engage position;
a first conduit coupling the second recess to a power takeoff clutch;
a sump;
a second conduit coupled to the first conduit;
and
a trimmer valve coupled between the sump and the second conduit and operative to couple the second conduit to the sump by an amount directly related to the rate of pressure increase of hydraulic fluid in the second conduit.

8 more elements

A power takeoff clutch modulating system comprising:

a power takeoff control lever;
a power takeoff modulating valve mounted within a bore and slidable in response to movement of the power takeoff control lever;
a source of pressurized hydraulic fluid;
a first recess in the bore coupled to the source of pressurized hydraulic fluid;
a second recess in the bore located adjacent and spaced apart from the first recess;
a groove in the modulating valve adapted to couple the first recess to the second recess when the control lever is moved into an engage position;
a first conduit coupling the second recess to a power takeoff clutch;
a sump;
a second conduit coupled to the first conduit;
a trimmer valve coupled between the sump and the second conduit and operative to couple the second conduit to the sump by an amount directly related to the rate of pressure increase of hydraulic fluid in the second conduit;
third and fourth spaced-apart recesses in the bore;
a third conduit coupling the first conduit to the third recess;
a second groove in the modulating valve adapted to couple the third recess to the fourth recess when the control lever is moved into an engage position;
a lock piston slidably disposed within a second bore and having opposite first and second ends, the first end of the lock piston being coupled to the control lever;
and
a fourth conduit coupling the fourth recess to the second bore adjacent the second end of the lock piston.

13 more elements

Dependencies are inferred from the claim text.

Clutch modulating system

Life of this patent

Clutch modulating system

Life of this patent

Abstract

Claims11