Patent GB-1428230-A (GB)
Title: Power assisted manual control systems for emergency brakes of  motor vehicles
IPC: B60T7/10
Filed: 1973-12-31
Abstract: 1428230 Combined manual and fluid-pressure brake operation; transmitting mechanism SOC ANON AUTOMOBILES CITROEN 31 Dec 1973 [12 Jan 1973] 60305/73 Headings F2E and F2F  A power-assisted manual control system for the emergency brake of a motor vehicle comprises a pivoting control handlever 1, a ratchet wheel 3 associated with a driving pawl 10 and a retaining catch 13, the ratchet wheel being operatively connected to a brake linkage 24, 27, and adapted to be mechanically actuated by the handlever when the latter is reciprocated, a control rod 18 associated with the handlever for releasing the retaining catch, and a fluid distributer valve 35 resiliently connected to the handlever and in communication with a main cylinder 29 for actuating the brake linkage and with a secondary cylinder 42 for actuating the driving pawl 10, the arrangement being such that, when the handlever is actuated in the brake-applying direction F, fluid under pressure is supplied on the one hand to the main cylinder 29 for actuating the brake linkage in the brake-apply direction (leftwards), and on the other hand to the secondary cylinder 42 for subsequently releasing the driving pawl from the ratchet wheel. As shown in Fig. 1, a handlever 1 pivoted at 2 has pivoted to it a rod 6 having a pin-and-slot connection 7, 44 with a plate 5 pivoted about the shaft 4 of a ratchet wheel 3 connected at 24, 27 to the brakes (not shown). Pivoted at 9 to the plate 5 is a driving pawl 10, and pivoted about a fixed pin 14 is a retaining catch 13 which may be manually disengaged from ratchet wheel 3 by rod 18 acting through a two-armed lever 16 pivoted at 17. An hydraulic circuit consists of a reservoir 39, pump 40, slide valve distributer 35, branch conduit 34a, conduit 34, main cylinder 29, flexible hose 41 and secondary cylinder 42 rigid with plate 5. Mechanical application of brakes with zero fluid pressure.-Handlever 1 is pivoted clockwise from the "brakes off" position (Fig. 1) so driving pawl 10 is released from stop 12 and urged by spring 11 into engagement with ratchet wheel 3, Fig. 2. On return of the handlever, wheel 3 is held by catch 13. The handlever is reciprocated between stops 22, 23, so the brakes are progressively applied by movement of linkage 24, 27 in direction f. Combined mechanical and fluid-pressure application.-Clockwise pivoting of handlever 1 always results in raising of spool valve member 36 through traction spring 38, so the output of pump 40, when fluid pressure is available, is connected via cylinder body 37 and conduit 34 with main cylinder 29, Fig. 3, so the brakes are applied via lever 25. Just prior to this happening, driving pawl 10 is released from ratchet wheel 3 by application of pressure fluid to secondary cylinder 42. The fluid pressure in conduit 34 and cylinders 29 and 42 is maintained proportional to the effort exerted on the handlever 1 by supplying fluid through branch conduit 34a to the region above spool valve member 36. The brakes are held applied after mechanical or mechanical-plus-fluid application simply by returning handlever 1 to the position of Fig. 1, where retaining catch 13 retains wheel 3 in the position it has reached with the brake on (Fig. 4, not shown) and fluid pressure in cylinders 29 and 42 is relieved by connection through valve distributer 35 to reservoir 39. For brake release from either kind of application, handlever 1 is first pivoted clockwise slightly, push knob 20 of rod 18 is then depressed against spring 21, and finally handlever 1 is returned to stop 22. This procedure ensures release of catch 13 from ratchet wheel 3, and counter-clockwise rotation of wheel 3, whichever method was used to apply the brakes.