Patent GB-1283725-A (GB)
Title: Brake control means
Inventor: LAVERDANT BERNARD
IPC: F16D65/56
Filed: 1969-10-22
Abstract: 1283725 Locking parking brakes SOC ANON DBA 22 Oct 1969 [23 Oct 1968] 51842/69 Heading F2E A vehicle emergency and parking brake system comprises a control member 62 controllable by an operator and having a looking device 66 also controllable by the operator for preventing release of the control member, and a resilient force-transmitting linkage 60, 64, 70 to 76 for connecting the control member to at least one brake 10-52 adapted to be normally actuated by a service braking system of the vehicle, the arrangement being such that operation of the control member stores energy in the resilient linkage for actuation of the or each brake when the service braking system ceases to actuate the or each brake. As shown in Figs. 1 to 3, a floating-caliper spot-type disc brake has a caliper 16 urged radially outwards by a spring 18, Fig. 3, against guiding members 20 co-operating with circumferentially opposed edges of an opening provided in a fixed support 10. The brake is normally actuated by hydraulic fluid admitted at 28, Fig. 2, between a piston 24 and the end of a cylinder forming part of caliper 16. Between the piston and the end of the cylinder is located a uni-directional automatic adjuster (see below). The caliper 16 is extended to form an arm 54 providing for emergency or parking control by means of a handle 62. Resilient means are inserted in the transmitting linkage between handle 62 and arm 54. Such means as shown consists of a pre-loaded spring 76 located between a piston 72 at the end of a rod 64 and one end 74 of a cylinder 70 telescoping with the rod. The assembly, designated 68, is thus of variable length, and is slidably mounted in a fixed portion 78 of the vehicle. The invention provides for two situations. If hydraulic pressure is not being applied (i.e. brake off), when handle 62 is pulled, caliper 16 is able to tilt by pivoting about a rib 50 on the outside of the backing plate of pad 14. Piston 24, which cannot move backwards because of its automatic adjuster, is therefore applied against rib 52 on the outside of the backing plate of pad 15. The brakes are thus applied. Spring 76 is strong enough to ensure that the assembly 68 behaves as a rigid rod in this situation. If hydraulic pressure is still being applied when handle 62 is pulled, the caliper cannot tilt because the pads 14, 15 are already in contact with the disc. Spring 76 is therefore compressed, and is retained in the compressed condition, when the handle is released, by engagement of ratchet 66 with rod 64. Whenever, subsequently, the hydraulic pressure is relieved, spring 76 is able to expand and push cylinder 70 and transmission system 60 downwards to tilt the caliper 16 to apply the brakes. A tension spring may be substituted for the assembly 68. Ratchet 66 may be unlocked by the operator to release the brake.  In Fig. 5 the resilient means is omitted from the hand-brake transmission-system connected to arm 92. Instead, the arm is pivoted at 94 to the caliper 90, and a torsion spring 96 normally urges projection 102 against stop 104. As before, when hydraulic pressure is absent, transmitting force applied to arm 92 in direction F causes tilting of caliper 90, and brake application, without stressing of spring 96. When hydraulic pressure is present, transmitting force causes stressing of spring 96, projection 102 parting from stop 104. When the hydraulic pressure is relieved, the spring 96 tilts the caliper to apply the brakes. The torsion spring 96 may be replaced by a compression spring, or Belleville washers, between arm 92 and a projection on the caliper. The automatic adjuster, Fig. 2, consists of a rod 30 solid with the end of the cylinder and having threaded on to it a sleeve 32; the thread is reversible and of large pitch. Piston 24 is capable of limited displacements with respect to sleeve 32 through the provision of a washer 34 retained by a snap ring; there is a thrust bearing 36 between the washer and a flange 38 on the sleeve 32, and a helical spring 40 around the sleeve and anchored at 42 in the piston, which is prevented from rotating. Spring 40 permits rotation of the sleeve 32 only in the direction of lengthening of the rod-sleeve assembly.