Abstract: An emergency axle lift control for a vehicle having at least one supplemental load axle configured to provide supplemental support to the vehicle by moving from a stored position in which wheels of the supplemental load axle do not contact the ground surface to a deployed position in which the wheels of the supplemental load axle contact the ground surface. The emergency axle lift control may comprise a control bypass switch operable by an operator of the vehicle while driving the vehicle, with the control bypass switch being configured to cause all of the supplemental load axles of the vehicle to move from the deployed position toward the stored position when the operator actuates the control bypass switch.

Abstract: The present invention is a pressure limiter for a hydraulic booster. The pressure limiter adjusts and limits the pressure generated between a pumping means and a restricting gap in a gain valve by limiting the size of the gap in response to sensed system pressure. A pressure limiter piston responds to system pressure to act against a gain valve piston and control the size of the gain valve gap.

Abstract: The present invention is a gain valve for a hydraulic booster which allows transition from a manual braking mode to a power assist braking mode without the control called for in the manual mode immediately applied when the power assist function begins to operate. This is accomplished by a bypass passage through the gain valve piston which prevents a pressure increase in the hydraulic booster for power assisted braking. The bypass passage automatically opens and resets in response to system pressures.

Abstract: The present invention is an improved hydraulic booster in which there is a ratio chamber between a power piston and a slave piston. The ratio chamber communicates with a low pressure fluid source through a check means which allows fluid from the low pressure fluid source to flow into the ratio chamber and prevents higher pressure fluid in the ratio chamber from flowing to the low pressure source. The check means can also be modified to allow air to be bled from the low pressure chamber.

Abstract: A hydraulic booster brake mechanism for use in an open center power steering system of a motor vehicle in which the booster brake mechanism employs a pressure regulating mechanism which limits the maximum pressure at which the booster operates to protect the hydraulic brake system and which operates to make the maximum pressure available when the pressure decreases. The pressure regulating mechanism operates to limit and to make available the maximum pressure when the pressure increases or decreases from a predetermined value by minimizing the effects of frictional forces and dynamic fluid flow by utilizing a control plunger which moves between open and closed positions on fluid trapped in a plurality of grooves which also act as seals. The fluid utilized by the booster is supplied to and delivered from additional grooves which not only assist the sealing grooves but minimize the effect of the flowing fluid.