Abstract: Clutch-brake steering unit having hydraulically actuated cylinders for controlling same to control rotation of a track-drive sprocket in a crawler tractor. Specifically a clutch cylinder and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arranged on a spring-applied-brake, hydraulically-applied-clutch basis that a single pressure signal in the inlet-outlet port alternately operates the cylinders to apply the brake and release the clutch, to apply the clutch and release the brake, or by proper modulation to partially engage either, i.e., slip the clutch or drag the brake to intermediate degrees as desired.

Abstract: A load supporting hydraulic system having main control valve provided with a load check valve and a vent valve; the load check valve, which has a hose connection to the main control valve, is operative to permit free flow of fluid from the control valve toward the load supporting chamber of the system and to block fluid flow from the load supporting chamber toward the control valve, whereas the vent valve is operative with the control valve to permit the load check valve to be opened by fluid pressure from the load supporting chamber to allow fluid flow therefrom thru the hose connection and control valve to drain. A cancelling valve is added to the system to override the vent valve upon failure of the hose connection and reblock fluid flow from the load supporting chamber toward the hose connection and control valve.

Abstract: Clutch-brake steering unit having hydraulically actuated cylinders for controlling same to control rotation of a track-drive sprocket in a crawler tractor. Specifically a clutch cylinder and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arranged on a spring-applied-brake, hydraulically-applied-clutch basis that a single pressure signal in the inlet-outlet port alternately operates the cylinders to apply the brake and release the clutch, to apply the clutch and release the brake, or by proper modulation to partially engage either, i.e., slip the clutch or drag the brake to intermediate degrees as desired.

Abstract: Hydrostatic tractor's drive and braking system, particularly one controlled, first, by a tractor safety lock lever which, when put "on," both neutralizes the engine-driven, variable ratio hydrostatic system for positively preventing drive and also sets the brakes for simultaneously positively preventing rolling and, second, by a two-stage brake pedal which is overcontrolled by the safety lock lever whenever the lever is "on" and which operates initially to intensify engine braking by increasing the hydraulically fixed ratio of the hydrostatic drive and its rate of dynamic dissipation of power, and which operates finally to neutralize drive and set brakes in an overlapping sort of way with the function of the safety lock lever and exactly the same as the safety lock lever does whenever "on.

Abstract: Clutch-brake steering unit having hydraulically actuated cylinders which are adapted for controlling same to control rotation of a track-drive sprocket in a crawler tractor, and which are under control of a clutch-brake steering valve mechanism. A bore in the valve is common to and receives both an independently slidable hydropotentiometer spool precisely providing a master setting pressure, and an independently slidable metering spool providing a single pressure signal always hydraulically matched with the precise master setting pressure. A clutch cylinder and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arranged on a spring-applied-brake, hydraulically-applied-clutch basis that the generated single pressure signal when applied to the inlet-outlet port alternately operates the cylinders to apply the brake and release the clutch, or to release the brake and apply the clutch, or by proper modulation to partially engage either, i.e.

Abstract: Booster providing both hydraulic feed-back and hydraulic feel-back in a two-stage operation in which we boost-brake a vehicle. Concentric, nesting, inner and outer control parts include, as the sliding outer part, a brake-pedal-connected input signal spool or sleeve for developing a desired signal pressure varying linearly along the length of, and therefore according to the sliding position of, the sleeve; the inner part constitutes a captive, telescoping metering spool with its ends in corresponding ends of the spool sleeve.

Abstract: Clutch-brake steering unit having hydraulically actuated cylinders for controlling same to control rotation of a track-drive sprocket in a crawler tractor. Specifically a clutch cylinder and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arranged on a spring-applied-brake, hydraulically-applied-clutch basis that a single pressure signal in the inlet-outlet port alternately operates the cylinders to apply the brake and release the clutch, to apply the clutch and release the brake, or by proper modulation to partially engage either, i.e., slip the clutch or drag the brake to intermediate degrees as desired.

Abstract: Clutch-brake steering unit having hydraulically actuated cylinders for controlling same to control rotation of a track-drive sprocket in a crawler tractor. Specifically a clutch cylinder and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arranged on a spring-applied-brake, hydraulically-applied-clutch basis that a single pressure signal in the inlet-outlet port alternately operates the cylinders to apply the brake and release the clutch, to apply the clutch and release the brake, or by proper modulation to partially engage either, i.e., slip the clutch or drag the brake to intermediate degrees as desired.

Abstract: Hydraulically operated steering systems normally supplied with fluid from an engine driven pump rely on an auxiliary pump upon failure of the primary pump. A ground driven pump incorporating a pressure sensing device automatically provides fluid to the power steering system in the event of an engine or primary pump failure.

Abstract: Frame-drawn scraper having a bowl with hydrospring suspension and hydraulic pump, comprising: bowl raise-lower means disposed between and connecting the scraper draft frame and bowl; and an intervening hose, accumulator, and motion sensitive blocking safety valve connected in circuit in that order from the pump to the bowl means, responsive to extreme lowering movement of the bowl if the hose ruptures, to hydraulically lock the bowl from farther lowering by automatically blocking the circuit.