Brake actuated shift control for mobile machines

• US 5,154,267 A
• Filed: 09/26/1991
• Issued: 10/13/1992
• Est. Priority Date: 09/26/1991
• Status: Expired due to Fees

• Current Assignee: Clark Equipment Company (Doosan Enerbility Company Limited)
• Original Assignee: Clark Equipment Company (Doosan Enerbility Company Limited)
• Inventors: Watts, Verne C.
• Primary Examiner(s): Bonck, Rodney H.
• Application Number:
  US07/765,593
• Time in Patent Office: 383 Days
• Field of Search: 192/4 R, 192/4 A, 192/1.44, 74/846
• US Class Current: 192/220
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 30/181 Preparing for stopping

Abstract

The present invention relates to a brake actuated shift control for mobile self propelled machines to reduce premature brake wear leading to brake failure caused when a brake is engaged and, during brake engagement, a transmission coupled to the machine transmits power to a coupled drive wheel engaging a surface. The transmission has a plurality of selectable ranges corresponding inversely to a plurality of transmission output torques. A shift actuation control is coupled to the transmission to cause the transmission to shift to a higher range when the brake is applied with the transmission in a low range, so as to reduce the transmission output torque.

Claims

1. Control means for reducing premature brake wear in a mobile machine having a hydrostatic transmission coupled to the mobile machine for transmitting rotational power to a coupled drive wheel engaging a surface, and which has a power operated shift between high and low transmission ranges comprising:

transmission shift actuation means coupled to the power operated shift of the hydrostatic transmission, the transmission having high and low ranges corresponding inversely to high and low transmission output torques; and

parking brake means responsive to parking brake actuation coupled to the transmission shift actuation means for causing the transmission when operated in the low range as the parking brake is applied to shift directly to high range when the parking brake is applied so as to reduce the transmission output torque when the parking brake is applied without shifting to a nondrive condition.

2. The apparatus of claim 1 wherein the transmission shift actuation means includes an electrically actuated hydraulic valve.

3. The apparatus of claim 1 wherein the brake actuation means includes a brake actuation lever.

4. The apparatus of claim 3 wherein a brake actuation lever switch operates when the brake actuation lever moves to an actuated position, the electrically actuated hydraulic valve being coupled to a brake actuation lever switch which in turn is coupled to the brake actuation lever.

5. A mobile self-propelled machine having a vehicle parking brake means adapted for use in conjunction with control means for reducing premature brake wear leading to brake failure, caused when a parking brake is substantially engaged and, wherein during such brake engagement, a mobile machine drive transmits rotational power to at least one drive wheel engaging a surface, comprising:

an operator compartment;

an engine;

a hydrostatic transmission coupled to the engine, the hydrostatic transmission having a transmission output and the transmission having a plurality of selectable ranges corresponding inversely to a plurality of transmission output torques selectable upon actuation of transmission shift actuation valve means, the transmission output being coupled to at least one drive wheel, the transmission shift actuation valve means being coupled in a hydraulic circuit for causing the fluid actuated transmission operated in a lower drive range to shift directly to a higher drive range when the parking brake means is actuated to reduce the transmission output torque relative to input torque; and

the parking brake means providing a braking action to restrict mobile machine movement when the parking brake means is applied, the parking brake means being coupled to the transmission shift actuation valve means for actuating the valve means when the parking brake means is applied.

6. The apparatus of claim 5 wherein the transmission shift actuation valve means comprises an electrically actuated solenoid coupled to a hydraulic valve.

7. The apparatus of claim 6 wherein the brake means comprises a brake coupled to a brake actuation lever, and a brake actuation lever switch coupled to the brake actuation lever and to the solenoid.