US 6,662,556 B2 · Hydraulic systems for a small loader

Abstract

A small self-propelled loader has hydraulic drive motors and at least one work cylinder, and has a hydraulic system that efficiently utilizes the available horse power from an internal combustion engine on the loader. The engine drives a tandem pump and the flows from two sections of the tandem pump pass through a first diverter valve that permits using the flow from each of the pump sections to drive a respective one of the drive motors. The return or drain flow from valves controlling the drive motors is connected to a second diverter valve to selectively direct the drain flow from the drive motors for operating remote work cylinders. Alternately, the first diverter valve directs the output from one pump section to the work cylinders, so that when the loader is standing still or moving very slowly, the work cylinder has adequate flow, and flow from the other pump section is split to power the drive motors. The motors and work cylinders are connected to separate relief valves so that a higher working pressure is available for the drive motors.

Claims20

Dependent claims

A hydraulic system for a power machine having a frame;

a drive motor for propelling the machine;
at least one work cylinder operated under hydraulic pressure;
a pump assembly;
a motor control valve connected to said pump assembly to receive flow from said pump assembly and operable to drive the motor, the motor control valve having a center flow through position, and at least a forward drive position for the motor;
a common drain line from the motor control valve to carry the flow from the motor control valve in the center flow through position and connected to receive return flow from the motor;
and
a diverter valve connected to selectively divert the flow from the common drain line to a cylinder control valve for controlling the work cylinder.

4 more elements

A hydraulic system for a self propelled machine having a frame;

a hydraulic pump assembly having separate pump sections providing separate flows;
first and second hydraulic drive motors;
first and second motor control valves connected to operate the first and second hydraulic drive motors, respectively;
a power source on the frame for powering the pump assembly of the hydraulic system;
a diverter valve having a first position for receiving the individual flows from each of the pump sections and directing individual flow from the pump sections to one of the first and second motor control valves, respectively;
a flow divider;
and
said diverter valve being shiftable to a second position to direct the fluid flow from a first of the pump sections to a flow divider, the flow divider providing divided flow to both the first and second motor control valves, and the diverter valve providing flow from a second pump section directly to a work valve on the machine for operating at least one work cylinder.

5 more elements

A loader having a frame and drive motors on opposite sides of the frame, the drive motors being individually selectably drivable, and the loader having at least one work cylinder operated under hydraulic pressure;

a pump assembly;
first and second valves connected to said pump assembly to receive substantially equal flow from said pump assembly, said first and second valves being operably connected to control rotation of the drive motors, the first and second valves each having a center flow through position, and at least a forward drive position for each of the motors, respectively;
a common drain line from both of the first and second valves to carry the flow from the first and second valves in the center through flow positions and the common drain line being connected to receive return from both of the drive motors;
and
a diverter valve connected to selectively divert the flow from the common drain line to a third control valve for controlling the work cylinder.

2 more elements

Dependencies are inferred from the claim text.

Hydraulic systems for a small loader

Life of this patent

Hydraulic systems for a small loader

Life of this patent

Abstract

Claims20