GB2044854A - Brake actuator particularly for agricultural trailers - Google Patents

Abstract

The actuator includes a ram (a) slidable in a cylinder and urged in the brake applying direction by a compression spring (d) disposed between fixed and slidable collars on the cylinder, the slidable collar being movable by rods (g) attached to the ram (a). Release of the brakes is effected by operating the normal hydraulic control valve to supply hydraulic pressure (b) to the space between the ram and the cylinder base (k) thereby to extend the rod (a). A hole (h) bored into the working face of the ram accommodates an oil return pipe (j) attached to the base (k) so that as the ram extends it moves along the return pipe until before the ram is fully extended a slot (l) in the pipe (i) is exposed allowing oil to return to reservoir. Thus the brakes are kept in an off position by a 'straight through' flow of oil. Cessation of pressure through control valve or pipe breakage causes the brakes to be applied by the pressure of spring (d) retracting the ram and forcing oil out of the cylinder. <IMAGE>

Description

SPECIFICATION Service, parking and safety brake applicator Designed as a service, parking and safety brake applicator which can be fitted to the majority of agricultural trailers or implements with cable or rod pull brakes.

System utilizes the standard hydraulic system of agricultural tractors with no appreciable strain.

Complies with : Motor Vehicles (Construction and Use Regulation 1978.) Regulation 75.

The brake applicator is a normal hydraulic ram. The ram is extended by hydraulic oil pressure compressing the spring between ram (I) and sliding collar (2) attached by two threaded rods.

The unique feature is the hole bored into the core of the ram from the pressure face.

Fixed into the end cap (3) is an oil return pipe (4) which the ram slides over.

As ram extends it moves up the return pipe until, before ram is fully extended, a slot cut into pipe is exposed allowing oil to return to reservoir thus allowing the brakes to be kept in off position by a 'straight through' flow of oil.

If hydraulic oil pressure is cut off by failure, hose breakage or control valve being reversed, the trailer brakes are applied by the back pressure of the spring forcing oil in chamber back through the inlet pipe thus putting tension on cable or rod attached to either or both ends of ram. When engine is stopped, brake will be applied by spring pressure forcing oil in .010" clearance between oil return pipe and core hole.

1. This brake applicator has a nominal working pressure using a continual fluid flow on 2 line system. To keep trailer brakes off.

2. Mechanism uses normal agricultural tractor hydraulic system and control lever.

3. Cessation of hydraulic pressure applies brakes. Consequently if pressure is released via control lever or if trailer becomes detached from tractor unit, (e.g. on an incline) brakes will automatically be applied.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Service, parking and safety brake applicator Designed as a service, parking and safety brake applicator which can be fitted to the majority of agricultural trailers or implements with cable or rod pull brakes. System utilizes the standard hydraulic system of agricultural tractors with no appreciable strain. Complies with : Motor Vehicles (Construction and Use Regulation 1978.) Regulation 75. The brake applicator is a normal hydraulic ram. The ram is extended by hydraulic oil pressure compressing the spring between ram (I) and sliding collar (2) attached by two threaded rods. The unique feature is the hole bored into the core of the ram from the pressure face. Fixed into the end cap (3) is an oil return pipe (4) which the ram slides over. As ram extends it moves up the return pipe until, before ram is fully extended, a slot cut into pipe is exposed allowing oil to return to reservoir thus allowing the brakes to be kept in off position by a 'straight through' flow of oil. If hydraulic oil pressure is cut off by failure, hose breakage or control valve being reversed, the trailer brakes are applied by the back pressure of the spring forcing oil in chamber back through the inlet pipe thus putting tension on cable or rod attached to either or both ends of ram. When engine is stopped, brake will be applied by spring pressure forcing oil in .010" clearance between oil return pipe and core hole. CLAIMS

1. This brake applicator has a nominal working pressure using a continual fluid flow on 2 line system. To keep trailer brakes off.

2. Mechanism uses normal agricultural tractor hydraulic system and control lever.

3. Cessation of hydraulic pressure applies brakes. Consequently if pressure is released via control lever or if trailer becomes detached from tractor unit, (e.g. on an incline) brakes will automatically be applied.