Title: Hydraulic actuating system for a pair of concurrently operating clutches or brakes

Abstract: Two concurrently operated hydraulic brakes of an automotive transmission, actuated in an intermediate-speed ("second gear") position, are filled under the control of a slide valve whose slider in a normal position admits fluid at high rate to both brakes and thereafter assumes an unstable throttling position in which the fluid pressure gradually builds up in them to a value causing an associated plunger to return the slider to normal. One of the brakes, which is only unidirectionally effective, remains actuated also upon an upshift into a high-speed position ("third gear") whereas the other, bidirectionally effective brake is released upon such upshift under the control of a shift valve which cuts off the fluid flow to the latter brake and establishes a drainage path therefor by passing the slide valve.

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Inventors: Dach, Hansjorg (Friedrichshafen, DT)
Furtner, Horst (Friedrichshafen, DT)
Marion, Robert (Lindau, DT)

Application Number: 395364
Filing Date: 1973-09-07
Publication_date: 1976-02-17
Assignee: Zahnradfabrik Friedrichshafen Aktiengesellschaft (Friedrichshafen, DT)
Primary Class(es): 475/122 475/129, 477/130, 477/150
Other Classes:
US Patent Ref:

3369430	Feb, 1968	Haley	74/867.
3453908	Jul, 1969	Iijima	74/867.
3494223	Feb, 1970	Mori	74/869.
3501979	Mar, 1970	Forster et al.	74/753.
3559669	Feb, 1971	Dach	74/753.
3593599	Jul, 1971	Dach	74/759.
3610070	Oct, 1971	Dach	74/753.
3670599	Jun, 1972	Nagamatsu	74/753.
3719108	Mar, 1973	Sakai	74/869.
3726157	Apr, 1973	Marumo	74/753.
3747439	Jul, 1973	Uozumi et al.	74/869.

Other Refs:
Primary Examiner: Scott, Samuel
Assistant Examiner: Chandler, Lance W.
Attorney: Ross; Karl F., Dubno; Herbert