Mannesmann Rexroth Corporation

G. L. Rexroth Gmbh

Ludwig Muncke

Wolfgang Kauss

Kurt Wittich

Norbert Mucheyer

Winfried Rub

Dietmar Gossl

Dietrich Radtke

Wolfgang Kaus

A process is described for application of pressure on setting mechanisms of transmission elements, e.g., band brakes or disk clutches, of an automatic transmission, particularly of the transmission system of a vehicle. In the process the control pressure applied to the setting mechanism is varied in dependence on the operating conditions. In order to eliminate transition errors and improve adaptation of the meshing behavior of the switching element, the slide of the switching element is regulated at a value adapted to the operating condition involved of the transmission and/or the vehicle. Apparatus for the implementation of the process is also described, as well as a hydraulic control system for supplying the operational chamber of a setting mechanism at a transmission element, which operational chamber has a continual leakage. In this regard, a valve device, by which the operational chamber can be rapidly filed by activation of the setting mechanism, is installed parallel to a rapid-response control valve, with which the pressure force of the transmission element parts can be influenced in a targeted manner. In this manner, it is possible for driver to feel a spontaneous reaction of the vehicle when activating the clutch or an autotmatic lever for switching between forward and reverse operation, without thereby detrimentally affecting the sensitivity and reaction time of the control valve.

Process and apparatus for regulating pressure application of setting

A hydraulic system is provided for powering a steering unit, a trailer brake and an auxiliary power unit from a single pump. A control circuit ensures that the hydraulic trailer brake and/or the power steering unit on the vehicle will operate on a preferential basis over the auxiliary power unit. The hydraulic control circuit has two priority valves connected in series. The upstream priority valve has a priority position in which it makes the pump fluid available to a supply line for the common priority flow for the steering and braking apparatus and a non-priority position for powering the auxiliary power unit. The common priority flow is passed through the second or downstream priority valve for priority powering of the power steering circuit.

Load sensing system with increasing priority in series of control valves

A hydraulic load power train control for reversible shifting with a pressure control device for the controlled build-up of a shift clutch pressure, a foot clutch valve for arbitrary control of the shift clutches, and a manually operable shift valve for shifting of the reversible power train. The foot clutch valve is connected parallel to the pressure control device. The pressure control device is formed by a changeover valve indirectly reversible by the shift valve by which the pressure controlled in the supply pressure line can be fed to two shift pressure lines which are connected to a valve device. At the same time, the valve device is so controlled by the foot clutch valve that the effective shift clutch pressure can be controlled without influencing the position of the changeover valve as a function of the actuation of the foot clutch. The hydraulic load power train control, on the one hand, makes possible, in the case of engaging or reversing of the shift clutches, a smooth transition from one gear to the other and, at the same time, a delay-free start in the shifting by actuation of the foot clutch.

Hydraulic circuit for the control of forward and reverse shift clutches

In a brake valve of the type in which a given ratio is maintained between a master pressure developed by a brake pedal and an actual brake pressure, an arrangement is provided for continuous, rather than stepwise, adjustment of this ratio. The brake valve includes a control piston which is subjected to the master pressure and which, by the displacement thereof, opens and closes connecting channels between an accumulator containing a primary pressure fluid and a brake, as well as between the brake and a fluid collecting tank. The control piston and a measurement piston apply counter forces to the arms of a balance beam whose lever ratio determines the degree of feedback of the instantaneous brake pressure to the control piston. A stop is provided in the path of the axis of the control piston, which limits the stroke of the piston, to prevent the overloading of the balance beam during abnormally high braking pressures such as occur, for instance, during panic braking.

Brake valve infinitely variable pressure intensification

In the supply of a power-assisted steering and an additional hydraulic system with fluid the power-assisted steering has priority so that when the steering is actuated the influx of fluid to the hydraulic system is correspondingly throttled by a priority valve. When a leak occurs in the hydraulic system, the influx of fluid to the hydraulic system is completely shut off when the oil level in the reservoir drops to a lower limit value. The closure of the priority valve is effected by a switch valve which is disposed in one of the control pressure lines of the priority valve and which is rendered currentless on response of the sensor for the fluid level.

Safety arrangement for power assisted steerings

Disclosed is a support unit for the cab of a utilitarian vehicle having a separate cab and chassis. The support unit includes a hydraulic piston and cylinder, including a compression spring, connected between the cab and the chassis. Fixed to the hydraulic support cylinder unit is a directional control valve which selectively directs and drains pressurized hydraulic fluid to or from the hydraulic support cylinder unit. The directional control valve is journalled to a lever pivoted to the cab. Also journalled to the lever are an elastically centered rod and an absorber element having an inelastically adjustable length. Dynamic fluctuations of the distance between the chassis and cab are opposed by the hydraulic support cylinder unit as actuated by the directional control valve. Static fluctuations in the distance between the chassis and the cab are accommodated by the hydraulic support cylinder unit together with the absorber element.

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Lohr/Main, Germany

Ludwig Muncke