Patent GB-1040819-A (GB)
Title: Retarder
IPC: F16D33/00
Filed: 1964-09-02
Abstract: 1,040,819. Hydrodynamic brakes; controlling friction clutches. EATON MANUFACTURING CO. Sept. 2, 1964 [Sept. 3, 1963; Aug. 10, 1964], No. 35997/64. Headings F2C, F2E, F2F and F2L. A rotary vane type hydrodynamic brake 14 for a heavy motor vehicle is mounted on the side of a gear-box 4 and driven from a gear-wheel on a shaft of the gear-box at a point ahead of at least one pair of changespeed gears, preferably from the input shaft, the brake using water from the engine cooling system, whereby the engine cooling radiator serves also to cool the brake. Pipes 58, 59 (Fig. 1, not shown) connect inlet and outlet ports on the stator casing to the water feed lines 11, 13 between the engine 2 and the radiator 9, to allow flow via chamber 53, stator vanes 51 which incorporate nozzles 54 (Fig. 5, not shown) and rotor vanes 44 of a rotor 42. In the embodiment of Fig. 3, the rotor is constantly driven from a gear-wheel 36 on the primary shaft of the gear-box via a gear 27 secured to rotor shaft 37. Control of the brake is then effected by valves 71, 73, 75 (Fig. 7, not shown) which are jointly operated by manual operating means 79, whereby either the valves 71, 75 are open with valve 73 shut, to allow flow of water through the brake and at the same time to charge a chamber 76 from a source S of compressed air, or valves 71, 75 are shut with valve 73 open to cause the charge of compressed air in chamber 76 to drive out the water from the brake. When the brake is refilled by opening valves 71, 75 and shutting valve 73, the air is removed by the circulating water to the engine radiator where it bubbles off. In the embodiment of Fig. 8, the brake is made operative by the engagement of a clutch in the rotor drive, and is regulated by a butterfly valve controlled by the pressure developed in the rotor chamber and which is also controllable manually. Clutches.-A self-gripping clutch arrangement is used in the embodiment of Fig. 8 to couple the rotor shaft 71 to an annular gear 72 which permanently meshes with the gear 31 or 36 (Fig. 3), the clutch comprising an annular housing 74 keyed to the shaft 71 and having a short inner flange 76 and a long outer flange 77, a ring 79 faced with friction material and slidable by pins 82 towards and away from a first sleeve 91 rotatable about the shaft 71, a relatively light helical spring 94 engaged between the first sleeve and one end 97 of a second sleeve 96 also rotatable about the shaft 71, guided between sleeve 91 and the outer flange 77, and a relatively strong helical spring 99 engaged between the other end 98 of the second sleeve and a retainer ring 103 which is secured to the gear 72 by a pin 104. The convolutions of the springs are such that they can normally rotate without gripping either the shaft 71 or the flange 77, but when ring 79 is moved into engagement with the sleeve 91, by rotation of a cam-shaft 88 having a cam 87 engaging a spider 83 to which the pins 82 are attached, spring 94 wraps itself around and grips the shaft 71, after which the heavier spring 99 expands into engagement with the flange 77. The flange 77 is preferably slitted longitudinally so that it expands in turn to grip the gear 72. Alternatively, where the clutch has to absorb less torque (where a smaller brake is used) the flange 77 may remain out of engagement with the gear 72 in which case the whole of the driving torque is taken by the pin 104 (Fig. 14, not shown). This would allow the gear 72 to be moved to a position between the clutch and the rotor of the brake where space is limited (Fig. 15, not shown). Combined clutch and brake control. Speedresponsive brake control.-For joint operation of the clutch and regulation of the flow of water through the brake the cam-shaft 88 controlling engagement of the clutch carries a pinion 132 engaging a rack bar 136 (Figs. 11 and 16, not shown) which is hollow to provide a cylinder 148 for a piston 149 carried by a rod 152. A rod 154 links rod 152 to a crank disc 157 having stops 161, 162 and which rotates a butterfly valve 158 (Fig. 17, not shown) in the water inlet 55 to the brake chamber. Piston 149 is normally held against the cylinder end wall by a spring 140 so that the rack bar 136 opens the butterfly on rotation of shaft 88 to engage the clutch, through the pinion 132. On build up of water pressure in the brake, however, the pressure is communicated from the brake chamber via a pipe 144 to an inlet 142 in the end of cylinder 148 to cause piston 149 to move rod 152 in the opposite direction to the previous movement of the rack bar 136, and so partially close the butterfly 158, thereby regulating the brake according to the speed of its rotor to cause an initial reduction of the degree of braking followed by increase of braking as the rotor speed decreases. Control of clutch and brake by compressed air.- In a further embodiment (Figs. 19, 20, 22, not shown) a compressed air system for combined brake and clutch control comprises a source S, a manually operable brake regulator valve 176 controlling flow of air to chamber 204, Fig. 20, of a control unit 172 mounted on the brake, to operate a piston 191 connected via rod 154d to crank disc 212 for opening inlet butterfly 158d, a relay valve 222 operated by pressure in the pipe 181 feeding the chamber 191 to control flow via a pipe 221 to a cylinder 226 containing a piston 227 which acts directly on the clutch energizing spider 83d, and a connecting pipe 144d between the brake chamber and an annular chamber 198 of the control unit 172 for opposing the movement of piston 191 with a force proportional to the speed of the rotor, whereby braking increases as speed of the rotor decreases.