Abstract:
A pressure assisted park servo assembly for an automatic transmission includes a servo or spool valve which receives pressurized hydraulic fluid from various sources including two solenoid valves and transmission ports. The servo valve controls two flows of pressurized hydraulic fluid to a servo assembly to place the transmission in or release it from park. The improved park servo assembly exhibits enhanced operating speed.
Abstract:
The invention relates to a pneumatic brake system 72 for a vehicle with brake cylinders 82, 84, which can be actuated with compressed air, for actuating wheel brakes, wherein a first group of wheel brakes belongs to a first brake circuit with a first compressed air storage tank 116 for providing a first stored pressure, and a second group of wheel brakes belongs to a second brake circuit with a second compressed air storage tank 130 for providing a second stored pressure, wherein at least one brake cylinder of the first brake circuit is embodied as a combined spring-store/diaphragm cylinder 84 with a spring store part 86 for providing a parking brake and a diaphragm part 88 for providing a service brake. In the event of a failure of the first brake circuit, the spring store part 86 can be deaerated in order to engage the parking brake. In order to simplify the brake system 72, a first pressure sensor 170 for measuring the first stored pressure is provided and connected to an electric control unit 80, by means of which a modulator 140 for aerating and deaerating the spring store part 86 can be controlled, wherein the control unit 80 is designed to generate an electrical control signal for an electrically actuable solenoid valve of the modulator if the value measured by the first pressure sensor 170 falls below a predetermined minimum pressure value, such that the spring store part 86 can be directly or indirectly aerated and deaerated by means of the solenoid valve 164. The invention also relates to a method for controlling a brake system of said type.
Abstract:
A distributed multi-range transmission is proposed which has one variator (1) designed as toroidal or friction gear variator, as band or chain variator, as cone ring transmission, or as continuously variable hydrostatic transmission, one planetary gear set (3) which engaged in power flow direction before the variator (1) serves as distributor transmission and engaged in power flow direction behind the variator serves as summarizing transmission for the power branches comprising shifting elements (K1, K2) which separately engaged, respectively engage the lower or the upper speed range, the power of the variator being conveyed to the output via a variator output transmission (2) or a shaft (6) situated paraxially with the variator and one direct or overdrive gear is provided in which no power flows via the variator and in direct gear or overdrive operation uncouples the variator from the power flow.
Abstract:
To retain a vehicle on an inclined roadway and when starting uphill, the vehicle speed, the brake pedal application, the drive torque, the operating condition of the vehicle engine, the application of a parking brake, and the activation of the retaining system is determined. When the retaining system is activated and the vehicle speed lies below a limit value, the brake force or the braking pressure is maintained when the brake pedal is applied and no drive torque is sensed; the brake force is increased when the driving engine is switched off and neither the brake pedal nor the parking brake is activated, or when the engine is switched on and neither brake pedal application nor drive torque is sensed. The brake force is reduced when the parking brake is applied, with the engine switched off and the brake pedal not applied, or a drive torque is sensed with the engine switched on. The retaining system is deactivated when the vehicle speed threshold is exceeded and/or when the off-switch is activated.A warning signal can be triggered by a door contact and/or a seat contact.
Abstract:
A motor vehicle is prevented from being parked with an unactivated parking brake. This vehicle has a roll-away preventer normally to apply a brake pressure which prevents the motor vehicle from rolling. To prevent unintentional rolling of the vehicle upon failure of the roll-away preventer, deactivation of the drive engine by using the ignition key is prevented when a brake pressure is not present to prevent the motor vehicle from rolling.
Abstract:
A pressure-holding valve for a brake system having a body with a blind bore therein. The body has a first passage which connects the blind bore with a variable pressure inlet port and a pressure outlet port. The blind bore is closed by seals carried on a plug having an axial passage therein connecting said inlet port with a second passage connected to the first passage. A non-return valve is located in said blind bore between the plug and the bottom of the blind bore while a valve controlled by an electromagnet is locate in the plug. In response to an operational signal the valve controlled by the electromagnet is moved into engagement with a seat to interrupt communication between the inlet port and the first passage. If the pressure holding valve is on an incline plane, the non-return valve moves to close the axial passage to prevent the return of pressurised fluid from the outlet port toward the inlet port and thereby maintain the fluid pressure in the system at a value of the fluid pressure at the outlet port to sustain a brake application.
Abstract:
When the vehicle speed falls below a predetermined reference speed, the measured vehicle deceleration is used to calculate an extrapolated time when the vehicle will be brought to a complete stop. When the extrapolated time is reached, the brake pressure is automatically applied and maintained until a desired departure is indicated.
Abstract:
A parking maintaining apparatus includes a solenoid-operated open/close valve which opens or closes a constant pressure passage providing a communication between a valve mechanism and a constant pressure chamber of a brake booster. A relief valve is provided which relieves a pressure within the constant pressure passage into the constant pressure chamber when such pressure exceeds a given value. The provision of the relief valve allows the pressure within a variable pressure chamber to be maintained at or below the given value through the valve mechanism under a parking maintaining condition, whereby the pressure within the variable pressure chamber can be rapidly displaced as the parking maintaining condition is to be terminated, thus eliminating a partly braked condition.