Braking systems for vehicles

Claim 2

A braking system for a tractor-drawn tipping trailer vehicle provided with hydraulically operated tipping gear, comprising spring means for applying each trailer wheel brake, means on the tractor vehicle for supplying hydraulic fluid under pressure through a hydraulic pressure line to release said wheel brakes against the action of said spring means, a control valve which is manually operable to vary the pressure at which said hydraulic fluid is supplied to said wheel brakes between a maximum at which the brakes are fully released and a minimum at which the brakes are fully applied, and a multi-position valve located in the hydraulic pressure line upstream of said control valve and manually operable to selectively direct fluid to said brakes and to said tipping gear.

Claim 3

A braking system according to claim 1, wherein said multi-position valve is operable to trap pressure fluid in the connection to said tipping gear while at the same time directing fluid to release said brakes.

Claim 4

A braking system for a tractor-drawn trailer vehicle, comprising spring means for applying each trailer wheel brake, means on the tractor vehicle for supplying fluid under pressure through an hydraulic pressure line to release said wheel brake against the action of said spring means and a control valve which is manually operable to vary the pressure at which hydraulic fluid is supplied to said wheel brakes between a maximum at which the brakes are fully released and a minimum at which the brakes are fully applied, said control valve comprising a valve casing, a spring-loaded ball valve in said casing having manually operable means to variably control a connection between said pressure line and a return line to fluid pressure supply on the tractor vehicle and means providing a small open bleed passage in said valve casing which maintains a constant connection between said pressure and return lines for ensuring substantially immediate application of the trailer wheel brakes in the event of failure of pressure derived from said pressure supply means in said tractor vehicle.

Claim 5

A braking system for a tractor-drawn trailer vehicle, comprising spring means for applying each trailer wheel brake, means on the tractor vehicle for supplying fluid under pressure through an hydraulic pressure line to release said wheel brake against the action of said spring means and a control valve which is manually operable to vary the pressure at which hydraulic fluid is supplied to said wheel brakes between a maximum at which the brakes are fully released and a minimum at which the brakes are fully applied, said control valve comprising a valve casing, a spring-loaded ball valve in said casing having manually operable means to variably control a connection between said pressure line and a return line to fluid pressure supply on the tractor vehicle and means providing a small open bleed passage in said valve casing which maintains a constant connection between said pressure and return lines for ensuring substantially immediate application of the trailer wheel brakes in the event of failure of pressure derived from said pressure supply means in said tractor vehicle.

Claim 6

A braking system according to claim 3, wherein said brakes are mechanically operated and said spring means exerts brake-applying pressure on the actuating rods of said brakes through at leAst one piston and cylinder device the cylinder of which is connected to said pressure line.

Claim 7

A braking system accordwng to claim 4, wherein said spring means comprises at least one compression spring.

Claim 8

A braking system according to claim 4, wherein said spring means comprises an assembly of belleville washers.

Claim 9

A braking system according to claim 3, wherein the loading spring for said valve member is held in compression between said valve member and a cup-like retainer slidably mounted in the valve casing in permanent engagement with a cam eccentrically mounted on the shaft of a lever manually rotatable through 180* to vary the loading of said spring.

Claim 10

A braking system according to claim 3, wherein said brakes are hydraulically operated and said spring means comprises a compression spring which exerts pressure on brake fluid in brake pipes leading to the individual brakes through the piston of a piston and cylinder device.