Patent GB-589056-A (GB)
Title: Braking system control means for vehicles
IPC: B64C25/48
Filed: 1944-10-19
Abstract: 589,056. Motor vehicle driving arrangements. BOLDT, W. F. Oct. 19, 1944, No. 20260. [Class 79 (ii)] [Also in Group XXIX] A fluid pressure braking system comprises a source of fluid pressure connected with two fluid motors by conduits which include a normally open shut-off valve for each conduit, a rotatable and slidable control shaft extending transversely to and between the axes of the valve elements and which on slight rotation in one or the other direction closes one or the other shut off valves, and two fluid pressure accumulators associated with the fluid motors which are placed in communication with the fluid motors by a sliding movement of the control shaft. The arrangement permits of braking to assist steering or of using both brakes together for parking. The general layout, shown in Fig. 1, includes a master cylinder 1 operated by pedal 3 and supplying fluid under pressure through the conduit 4 to the control valve 11 and thence to the conduit 5, 6 leading to fluid motors 7, 8 actuating the brakes. The control valve 11 comprises a shaft 38, Fig. 2, which can be rotated together with the collar 42, embodying a stop, in either direction by means of the handle 48; or it can be axially displaced against the spring 41 by raising the handle 48 to which is attached a fork 51 embracing a pin 52 on the control shaft. The shaft 38 extends between a pair. of horizontal cylinders, Fig. 3, each comprising a valve member 27 which is axially displaceable upon rotation of the control shaft 38 by the wing member 46. Each valve member 27 has a stem 28 to the end of which is secured a perforated cage 29 containing a ball 33 which is spring-urged on to the seating 31 to close the orifice 32. The cage 29 is normally held in the position shown by spring 35 whereby the valve member 30 is held off its seating and the passage 16 kept open, whilst the valve member 36 is held on to its seating to close the passage 24 leading to a fluid pressure accumulator comprising a piston 22 backed by a spring 23 and working in the cylinder 21. The chamber 13 is in communication with the supply pipe 4, and the chamber 14 is in communication with the conduit 5. When. the handle 48 is in its central position the parts are disposed as shown in Figs. 2 and 3, and the supply pipe 4 is in free communication with conduits 5 and 6,. so that operation of the pedal 3 causes both brakes to be applied. If the handle is swung round to rotate the control shaft 38, the wings 46 move one or other of the valves 27 to close one of the orifices 16 or 18 whereby one of the conduits is cut off and operation of the pedal 3 causes the other brake only to be applied, to assist steering. Owing to the size of the slots 47, a slight rotation of the shaft 38 and wings 46 affects one valve 27 only. If the handle 48 is raised, the shaft 38 is depressed axially and causes the wing 46 to move both valves 27 to the right; this causes the valve members 30 to close passages 16 and 18 and to open passages 24. The foot pedal may then be pumped to force fluid past the one-way ball valve 33 and to move the piston 22 to compress the spring 23, at the same time both brakes are applied. The balls 33 are held on their seats and the pressure is maintained in both conduits 5, 6 to keep the brakes on, the valves 27 are then kept in the right-hand position irrespective of the position of the handle 48; any small leakage is compensated by the accumulator 20 or 25. To release the brakes, the pedal is operated until the pressure in the supply pipe 4 at least equals that in the conduits 5 and 6, the handle 48 is lowered, and the spring 30 then moves the valves 27 back towards the positions shown and the pressure is released.