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HYDROSTATIC TRANSMISSION CLUTCH ENGAGEMENT USING A LOAD SHUTTLE VALVE

IP.com Disclosure Number: IPCOM000236477D
Publication Date: 2014-Apr-29
Document File: 3 page(s) / 64K

Publishing Venue

The IP.com Prior Art Database

Abstract

This concept is an improved design to actuate the final drive clutches used on hydraulically driven front wheels on motor graders through the use of load shuttle valves which select the highest pressure from the first and second inlets of the wheel-driving hydraulic motors and direct that pressure to the corresponding drive clutch. This essentially ensures that the highest pressure inlet is always directly connected to the valve outlet and consequently to the clutch pack creating a simple way to engage final drive clutches whenever the corresponding hydraulic motor is receiving pressurized fluid.

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HYDROSTATIC TRANSMISSION CLUTCH ENGAGEMENT USING A LOAD SHUTTLE VALVE

Concept Summary:

This concept is an improved design to actuate the final drive clutches used on hydraulically driven front wheels on motor graders through the use of load shuttle valves which select the highest pressure from the first and second inlets of the wheel-driving hydraulic motors and direct that pressure to the corresponding drive clutch. This essentially ensures that the highest pressure inlet is always directly connected to the valve outlet and consequently to the clutch pack creating a simple way to engage final drive clutches whenever the corresponding hydraulic motor is receiving pressurized fluid.

Background:

Construction vehicle such as motor graders can be provided with hydrostatic front wheel drive to enhance tractive effort when performing work. Typically, each front wheel is equipped with a hydraulic motor controlled for selective engagement with the wheel via a clutch. When the clutches are engaged for work, each motor powers a final drive to reduce speed and increase output torque on the respective wheel. When disengaged, such as during transport travel, the final drive is in a free-wheel condition. The clutches used to physically effect engagement or disengagement of the final drive often require hydraulic pressure to actuate. Certain designs may utilize a three position valve to shuttle flow from either side of the hydrostatic loop to the final drive clutch. This involved more complex components, as well as more complex software and extra control solenoids, in order to determine which side of the hydrostatic loop is at the highest pressure and directing that pressure to the final drive clutch. This concept discloses the use of a load shuttle valve to utilize existing left and right hydrostatic loops as the pressure source for each wheel without the need for sensors, software, or algorithms.

Concept I...