Abstract: Controller and control method for improving operability at a time when a brake force that is retained in hill-hold control is reduced. A control section for executing the hill-hold control that retains the brake force on an inclined road surface is provided. The control section cancels retention of the brake force in the case where it is determined on the basis of a detection signal of a first detection mechanism that a first operation section for operating a brake mechanism is operated when the brake force is retained in the hill-hold control.

Abstract: A pneumatic vehicle brake system includes first and second groups of wheel brakes belonging, respectively, to first and second brake circuits having first and second compressed air storage tanks for providing first and second stored pressures. At least one first circuit brake cylinder is a combined spring-store/diaphragm cylinder with a spring store part for providing a parking brake and a diaphragm part for providing a service brake. If the first circuit fails, the spring store part is deaerated to engage the parking brake. A pressure sensor for measuring the first stored pressure is connected to a control unit that controls a modulator for aerating and deaerating the spring store part. The control unit generates a signal for an electrically actuatable modulator solenoid valve if the value measured by the sensor falls below a minimum value, such that the spring store part can be aerated and deaerated via the valve.

Abstract: An electropneumatic control arrangement for an automatic vehicle level control system, particularly of a commercial vehicle, includes at least; a solenoid valve unit having at least two electropneumatic solenoid valves, a compressed air inlet for infeeding compressed air, at least one compressed air connection for at least one air bellows and electrical control inputs, and an electronic control unit for actuating the solenoid valve unit. The electronic control unit comprises control outputs for electrically connecting to the control inputs of the solenoid valve unit. A plug connector is configured on the housing of the solenoid valve unit, in which the electrical control inputs are disposed, and a plug connector is provided on the housing of the electronic control unit, in which the control outputs are disposed. The plug connectors are mechanically plugged into each other.

Abstract: A drive system of a working vehicle including a main engine drivingly connected to a hydraulic pump. The hydraulic pump is connected to first and second hydraulic motors. When an undesirable operating condition is detected, a control device shifts an actuator associated with at least one of the wheels, to reduce the displacement volume of the hydraulic motors driving that wheel. In addition, shifts are made in the actuator of the respective other hydraulic motor and/or in the actuator of the hydraulic pump, in order to maintain a constant speed of travel. The control device shifts the actuator of the hydraulic motor of the other wheel toward greater displacement, and if that shift is insufficient to compensate for the undesirable operating condition, the control device will shift the actuator of the hydraulic pump in the direction of reduced displacement volume.

Abstract: The invention relates to a process and a system for aiding a starting movement of a vehicle. Problems occur particularly when starting on a hill or on a steeply sloping road because it is difficult or impossible for the vehicle operator to simultaneously release the foot brake pedal and operate the accelerator pedal and thus provide an engine torque necessary for the corresponding starting operation. It is an object of the invention to provide a process and a system for aiding a starting movement of a vehicle by means of which the starting movement can be carried out without problems and in an uncomplicated manner and without endangering other traffic participants. In the process and system according to the invention, this is achieved in that the rest position of the vehicle is ensured by means of a braking intervention by way of an external power or secondary brake circuit if the braking force exercised by the vehicle operator is not sufficient.

Abstract: A system to control the operation of a vehicular transmission embodying the concepts of the present invention utilizes a controller, at least one pulse width modulation solenoid valve and a torque transfer device operatively controlled by each of the solenoid valves so as to regulate a transmission system. The controller operatively imposes not only a varying modulation frequency on each of the solenoid valves, but also a varying modulation duty cycle on each of the solenoid valves. The controller also operatively varies the modulation rate of said frequency and said duty cycle of the fluid pressure operating the plurality of torque transfer devices, thus controlling the operation of each solenoid valve such that it does not impose a torque spike on the operation of the transmission as each solenoid valve applies fluid pressure to the appropriate torque transfer device. Accordingly, the controller provides smooth and quiet operation of the transmission.

Abstract: An electronically controlled hydrodynamic retarder interconnects with the output shaft of a vehicle transmission to selectively apply a braking torque thereto. The retarder includes a solenoid valve, the operating duty cycle of which controls the retarder capacity and resultant braking torque. A control unit, interconnecting the transmission and the retarder, regulates the duty cycle of the solenoid valve to regulate the retarder operation as a function of excessive deceleration or overheating, while also regulating such operation during downshift to assure efficient, effective, and comfortable operation of the transmission/retarder. The retarder is adaptive to accommodate variations resulting from age, wear, and the like.

Abstract: A brake fluid pressure control apparatus is disclosed which is capable of providing a good brake feel at the initial stage of pressure reapplication. The brake fluid pressure control apparatus comprises a pressure receiving device 25 and a valve mechanism 19 for closing a fluid passage 10 from a master cylinder 7 to wheel cylinders 8. The wheel cylinder fluid pressure is held by closing the fluid passage when the vehicle is brought to a halt with the brake applied, so that the vehicle can be held stationary if the driver takes his food off the brake pedal. When the pressure is to be applied again from the master cylinder 7, the pressure applied during the initial period of this reapplication of the master cylinder pressure is received by the pressure receiving device.