Abstract: A traction control system used to control a hydraulically propelled vehicle having front and rear drive assemblies has a variable displacement hydraulic motor coupled to each drive assembly. The hydraulic motors are connected in parallel to a pump. A control system senses the speed and direction of each motor as well as the grade of the ground surface. The controller uses this data to control the front and rear hydraulic motors. If the controller determines that one of the drive axles is slipping, it will destroke that axle's motor. However, if the vehicle is traveling downhill, the downhill drive assembly will not be destroked.

Abstract: A variable pressure control for controlling displacement of a variable displacement over-center pump utilizes a pair of remotely variable pressure limiter three-way valves which are associated one with each of a pair of servo cylinders operably connected to a swash plate of the pump and acting in opposition for positioning of the swash plate. The pressure limiter valves each control the communication of a servo cylinder with either system pressure or drain and are remotely operable to set a displacement of the pump and limit the pressure of the fluid delivered by the pump. This structure enables setting of pump displacement without the use of a displacement control valve associated with the servo cylinders.

Abstract: A multi-function valve usable in a hydrostatic transmission and having valve components mounted in a single valve body to provide pressure limiter and high pressure relief functions and with the structure also providing a bypass function and for supply of makeup fluid to the hydrostatic transmission. The multifunction valve has a charge check valve member and a relief valve member in associated relation and movable upon the occurrence of a predetermined pressure differential thereacross to perform control functions. One pressure differential results from a flow through an orifice and with the flow being controlled by a poppet valve member normally held closed by a heavy spring which establishes a system pressure at which the pressure limiter function will occur. With this structure, the pressure limiter function occurs in advance of the high pressure relief function and under the control of a single heavy spring.

Abstract: A multi-function valve usable in a hydrostatic transmission and having valve components mounted in a single valve body to provide pressure limiter and high pressure relief functions and with the structure also providing a bypass function and for supply of makeup fluid to the hydrostatic transmission. The multi-function valve has a charge check valve member and a relief valve member in associated relation and movable upon the occurrence of a predetermined pressure differential thereacross to perform control functions. One pressure differential results from a flow through an orifice and with the flow being controlled by a poppet valve member normally held closed by a heavy spring which establishes a system pressure at which the pressure limiter function will occur. With this structure, the pressure limiter function occurs in advance of the high pressure relief function and under the control of a single heavy spring.

Abstract: A pressure limiter for a variable displacement pump of a hydrostatic transmission and which is remotely variable and operable to reduce pump stroke when a system pressure limit is exceeded to limit torque applied to an output shaft of the transmission. The pressure limiter has a valve with a valve member which senses system pressure and when system pressure exceeds a certain value the valve member operates to direct system pressure to a servo cylinder for the variable displacement pump to move the swashplate of the pump in a destroking direction. The pressure limiter valve has a spring acting on the valve member in a direction opposite to the force of system pressure and a piston is associated with the spring. A remotely set variable control pressure can be applied to the piston to vary the effective force of the spring and value of system pressure at which the pressure limiter valve will open to destroke the pump.

Abstract: An arrangement for inhibiting low temperature gas-side corrosion of an out of service steam generator and its heat exchange and gas clean-up adjuncts. The arrangement provides for circulating pressurized heated air through the steam generator and its adjuncts, controlling the pressurization of the air to maintain positive gas-side pressure, controlling the heating of the air to maintain gas-side surfaces above the dew point, and returning the air which has passed through the steam generator and its adjuncts to the forced draft fan to be repressurized, reheated and reintroduced into the steam generator.