Patent GB-181671-A (GB)
Title: A valve for automatically adjusting the brake power of an automatic vacuum braked vehicle according to the gross load of the vehicle
IPC: B60T13/46
Filed: 1921-10-12
Abstract: 181,671. Pinder, T. June 13, 1921, [Convention date]. Fluid-pressure.-To limit the braking pressure on a vehicle in accordance with the load, a valve is provided adapted to cut off the train-pipe from the lower chamber of the vacuum brake cylinder when the pressure in that chamber has reached a value determined by a spring the tension of which may be adjusted manually or by the movement of the vehicle on the bearing springs. The valve may also be controlled by the actuating member of a hand release valve of the usual type so as to permit re-application of the brakes, after release, on a detached vehicle. In the form shown in Fig. 1 the valve H controlling a passage between the train-pipe and the lower chamber of the brake cylinder, connected at B and C respectively has a rod J connected to a diaphragm D enclosing a chamber E in which the initial trainpipe vacuum is established through a ball-valve K. The valve H is urged to the open position shown by a spring L, abutting against a nut M on the rod J. The nut M may be turned to adjust the tension of the spring by a washer N having a wedge-shaped face engaging a correspondingly shaped face on the nut. The washer may be turned by a rod O or an arm P connected to the vehicle springs or some other part which moves in accordance with the load or the rod O may be extended to the side of the vehicle for adjustment by hand. When in applying the brakes, the increase of pressure in the train-pipe and the lower chamber of the brake cylinder acting on the diaphragm D is sufficient to overcome the spring L, the valve II closes and prevents any further admission of air to the brake cylinder. Fig. 3 shows one arrangement in which the valve H is adapted to be operated also with a release valve U. The tension of the spring L is adjusted by an arm O and the chamber E is shown as connected to the upper chamber of the brake cylinder by the passages W, V to dispense with the ball-valve K. The release valve U which is normally closed by the spring Y to cut off the upper brake cylinder chamber from the lower chamber connected at C can be opened by hand when it is desired to release the brakes by projections C' on a sliding rod A<1>. The valve H has a stem H<1> slidably mounted on the rod J and provided with projections S one of which is engaged by a cam Z on the rod A<1> when the release valve U is opened, to close the valve H if it should be open and prevent the entry of air to the brake cylinder through the train-pipe chamber B, when the pressure in the chambers thereof are equalized. To re-apply the brakes the rod A' is moved inwardly so that the lower projection S is engaged by the cam Z and the valve H thereby opened to admit air by way of the train-pipe to the lower brake cylinder chamber. The valve H operates as described with reference to Fig. 1 to limit the admission of air to the brake cylinder in accordance with the load under the action of the spring L and the diaphragm D. In another form of the apparatus the chamber E is dispensed with, the upper side of the diaphragm D being open to the atmosphere the spring in this case acting to close the valve H and its tension being diminished as the load is increased. In this arrangement the valve rods A<1>, H<1> are actuated by crank arms on a manually operated spindle.