Clutch and brake inching control

Claim 1

A control apparatus for a vehicle having a transmission with fluid actuated clutch means and hydraulic brake means, comprising: a source of fluid pressure including fluid pressurizing means therefor; a first fluid conduit connecting said pressure source with said clutch means; a fluid pressure control valve assembly disposed within said first fluid conduit for automatically controlling fluid pressure being discharged from said pressure source and for delivering the controlled fluid pressure to said clutch means; a fluid actuated inching valve assembly disposed within said first fluid conduit for activating and de-activating said clutch means, said inching valve assembly comprising a housing provided with an axial bore therein, a spool valve axially slidably mounted in said bore and provided with first and second lands which are slidably fitted in said bore, first and second smaller diameter lands which respectively serve as variable orifices with respect to an inside wall of said housing, a first drain port disposed within said housing and closed by said first land in the rest position of said spool valve, said first and second smaller diameter lands respectively regulating said controlled fluid pressure to said first drain port and to said fluid actuated clutch means, a drain chamber in said bore between said first land and one end wall of said housing formed with a second drain, a spring interposed within said drain chamber urging said spool valve in one direction, a hydraulic pressure chamber formed between said first and second lands kept in fluid communication with said first fluid conduit in the rest position of said spool valve, a chamber formed between said second land and an inside wall of said housing, and a projection of said valve normally contacting said inside wall of said housing in the rest position of said spool valve; and a tandem master cylinder fluidically connected to said brake means and mechanically connected to a brake pedal, said tandem master cylinder independently including a first chamber connected to wheel brake cylinders of said brake means through a second fluid conduit and a second fluid chamber connected to the chamber between the second land and the inside wall of the housing of said inching valve assembly through a third fluid conduit, whereby even when said third fluid conduit is damaged, braking force may be obtained in accordance with the operation of the brake pedal.