US 6,283,263 B1Granted

Clutch and brake control system for tracklaying construction vehicle

AssigneeKomatsu Ltd.

InventorToshio Ibuki

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Abstract

A clutch and brake control system for a tracklaying construction vehicle is disclosed, which comprises a turning operation system and a driving brake operation system. The turning operation system is operative to carry out slow turning steering and quick turning steering of the vehicle by controlling clutches provided for right and left crawler belts for the purpose of transmitting driving force to the crawler belts and controlling brakes provided for right and left crawler belts for the purpose of stopping the rotation of the crawler belts. The driving brake operation system is operative to stop the vehicle by actuating only both of the brakes. To simplify a control linkage extending from an operating section to valves thereby reducing looseness and deflection to improve operability, the brakes are each composed of (i) a steering brake valve for carrying out brake releasing or brake actuation by delivering or reducing fluid pressure with respect to a brake hydraulic circuit according to the operation of the turning operation system and (ii) a driving brake valve for carrying out brake actuation by reducing fluid pressure in the brake hydraulic circuit according to the operation of the driving brake operation system.

Claims9

Dependent claims

A clutch and brake control system for a tracklaying construction vehicle, comprising a turning operation system and a driving brake operation system,

the turning operation system being operative to deliver a fluid pressure from an oil pressure source to either of clutches or remove a fluid pressure therefrom, the clutches being provided for right and left crawler belts for the purpose of transmitting driving force to the crawler belts, so that engagement or disengagement of said either one of the clutches is carried out to slowly turn the vehicle,
the turning operation system being also operative to reduce a fluid pressure delivered from the oil pressure source to either of brakes which are provided for right and left crawler belts for the purpose of stopping the rotation of the crawler belts, so that said either one of the brakes is actuated to quickly turn the vehicle,
the driving brake operation system being operative to reduce a fluid pressure delivered from the oil pressure source to only both of the brakes so that both brakes are actuated to stop the vehicle,
the clutch and brake control system comprising, in a brake hydraulic circuit extending from the oil pressure source to the brakes, steering brake valves for delivering a fluid pressure into the brake hydraulic circuit to release the brakes or reducing a fluid pressure within the brake hydraulic circuit to actuate the brakes, in accordance with the operation of the turning operation system and driving brake valves for reducing a fluid pressure within the brake hydraulic circuit to actuate the brakes in accordance with the operation of the driving brake operation system, and
wherein said steering brake valves are positioned on the upstream side of the brake hydraulic circuit while said driving brake valves are positioned on the downstream side of the brake hydraulic circuit.

2 more elements

A clutch and brake control system for a tracklaying construction vehicle, comprising a turning operation system and a driving brake operation system,

the turning operation system being operative to deliver a fluid pressure from an oil pressure source to either of clutches or remove a fluid pressure therefrom, the clutches being provided for right and left crawler belts for the purpose of transmitting driving force to the crawler belts, so that engagement or disengagement of said either one of the clutches is carried out to slowly turn the vehicle,
the turning operation system being also operative to reduce a fluid pressure delivered from the oil pressure source to either of brakes which are provided for right and left crawler belts for the purpose of stopping the rotation of the crawler belts, so that said either one of the brakes is actuated to quickly turn the vehicle,
the driving brake operation system being operative to reduce a fluid pressure delivered from the oil pressure source to only both of the brakes so that both brakes are actuated to stop the vehicle,
the clutch and brake control system comprising paired right and left steering valves provided for one steering operation lever, each steering valve being composed of a steering clutch valve of the variable fluid pressure reducing operation type for controlling fluid pressure for clutch disengagement and a steering brake valve of the variable fluid pressure reducing operation type for controlling fluid pressure for brake actuation,
the right and left steering clutch valves being connected to the right and left clutches respectively within a steering clutch hydraulic circuit,
the right and left steering brake valves being connected to the right and left brakes respectively within a steering brake hydraulic circuit,
the clutch and brake control system comprising right and left driving brake valves of the variable fluid pressure reducing operation type which are positioned in series within a hydraulic circuit downstream of the right and left steering brake valves, and
the right and left driving brake valves being simultaneously controlled by a foot pedal.

5 more elements

Dependencies are inferred from the claim text.