Abstract: A hydraulic brake actuator including a hydraulic parking brake that can be applied by mechanically locking up either a normal service brake application or a hand pump operated brake application. The lock-up mechanism includes a friction collar that surrounds the piston push rod and a hand pump actuated locking member that surrounds the friction collar. The friction collar and locking member have complementary conical surfaces that are engageable when hydraulic hand pump pressure is applied to a piston face of the locking member to wedge the friction member into pressure engagement with the piston push rod, as a means of locking up the push rod to obtain a parking brake. The locking member also includes a plurality of spring-like fingers that project axially from the periphery of the locking member and are provided with latching tabs adapted to enter a recess in the body to prevent return-movement of the locking member when the hydraulic hand pump operation is terminated.

Abstract: A combined hydropneumatic brake cylinder/air reservoir device having a hydraulic piston formed on the end of a push rod through which interconnected, different sized, pneumatic pistons operate to transmit the desired brake force. The hydraulic piston operates in a hydraulic cylinder having a slack adjuster piston arranged to supply or reduce the hydraulic fluid in the braking circuit in order to compensate for overtravel and undertravel of the pneumatic piston assembly due to brake shoe wear and brake shoe replacement respectively. The double-acting slack adjuster action results in the stroke of the pneumatic piston assembly being maintained constant to assure continued optimum operating efficiency.

Abstract: A manually-operable pressure-regulating valve device, including a special handle mechanism and a self-lapping valve assembly having a feedback piston on which delivery pressure acts to urge the valve assembly actuating stem in a direction opposite handle pressure, thereby transmitting to the operator a "feel" of the effective delivery pressure. The handle mechanism includes an elongated lever for operating the self-lapping unit with mechanical advantage to reduce operator fatigue. The elongated lever is made flexible, so that movement of the self-lapping valve assembly toward lap position, following actuation thereof, is absorbed by flexure of the elongated lever in order to, in effect, isolate the handle from the self-lapping unit in terms of movement without losing handle "feel" of the delivery pressure acting on the self-lapping valve assembly.

Abstract: A disk brake actuator having a hydraulic slack-adjusting arrangement for maintaining a positive clearance between a brake shoe and a brake disk, includes a cylinder housing having disposed therein a brake-applying spring section, a hydraulic-operated release section, and an actuator piston spindle arrangement operably-connected to the spring section by way of a clutch arrangement. A flange, formed on the actuator piston, acts as a plunger during a brake application and draws a first amount of hydraulic fluid into a first storage area, such first amount corresponding in volumn to the clearance between the brake disk and brake shoe when a nonworn brake shoe is first used. Upon release of the brake, the actuator piston forces the hydraulic fluid back into a second storage area wherein is included a shuttle member movable with a shuttle chamber. Additional hydraulic fluid is drawn from a reservoir when actuator piston movement, beyond the original clearance value, occurs as a result of brake shoe wear.

Abstract: An automatic reset arrangement for a manual release mechanism in a spring-applied, air-released brake comprising a sleeve member having axially projecting fingers that slide axially within the bore of the spring piston push rod. The ends of the projecting fingers are formed with outturned lugs having a conically-shaped surface adapted to engage a correspondingly-shaped shoulder in the bore of the piston push rod to provide a drive connection through which the spring brake force is transmitted to the sleeve member. A cylindrical plug member is normally arranged within the sleeve member at the flange end thereof to prevent inward deflection of the fingers and to thus maintain the integrity of the drive connection. A spring-returned, manually operable release lever is arranged to withdraw the plug member when it is desired to release the spring brake in the absence of air.

Abstract: A two-stage, hydro-pneumatic actuator suitable for use as a railway vehicle brake. The hydraulic cylinder comprises a large diameter bore in which a low- and a high-pressure piston operate jointly during a first stage of operation to effect a high volumetric displacement of hydraulic fluid via a small diameter bore in order to take up the clearance between the brake shoes and wheel. As the brake shoes contact the wheel, the high-pressure piston enters the small bore to interrupt further displacement of hydraulic fluid from the large bore. The force of the high-pressure piston alone during this second stage of operation produces the required brake forces with a high multiplication factor. Make-up fluid is drawn into a chamber on the backside of the low-pressure piston during a brake application stroke an amount corresponding to the over-travel of the high-pressure piston and is subsequently discharged into the hydraulic cylinder during retraction of the brakes to compensate for brake shoe wear.

Abstract: In a brake actuator device having a fluid pressure actuated service brake and a spring-applied, fluid pressure released auxiliary brake that cooperates with the service brake via a friction clutch mechanism, there is provided a manual release mechanism for releasing the spring-applied brake in the absence of fluid pressure. The manual release mechanism operates to relieve the tension of the actuating spring by causing the piston through which the spring operates to engage a stop formed on the casing of the brake actuator device, so that the spring is caged at its opposite ends by the casing of the brake actuator device. Extension of a retracting screw to initiate the manual release operation is automatically retracted following engagement of the spring piston with its stop to reset the manual release mechanism in readiness for a subsequent operation.

Abstract: A hydro-pneumatic brake actuator arranged with a slack adjuster piston and one-way check valve device in the hydraulic path between a hydro-pneumatic actuator and a power piston, to which a friction brake element is connected for engagement with a vehicle wheel tread or brake disc during a brake application. During a brake release, the one-way check valve closes a passage through the slack adjuster piston to cause the piston to shift from its one extreme position to the other extreme position with the fluid flow, as the hydro-pneumatic actuator is moved from its application position to its release position. This in turn draws hydraulic fluid from the power piston chamber into a clearance volume created by shifting of the slack adjuster piston, and accordingly forces the power piston to retract a predetermined distance corresponding to the capacity of the clearance volume and the effective area of the power piston, thereby maintaining a constant brake shoe clearance during brake release.