Patent GB-960671-A (GB)
Title: Improvements relating to hydrodynamic brakes
Inventor: SINCLAIR HAROLD
IPC: F16D57/04
Filed: 1962-07-09
Abstract: 960,671. Hydrodynamic brakes; chance-speed gearing. J. M. VOITH G.m.b.H. July 9, 1962, No. 26316/62. Addition to 934,106. Headings F2D and F2E. The hydrodynamic brake of the parent Specification is modified for application to change-speed gearing in a ship or stationary driving gear, for braking a driving shaft after power has been cut to speed up synchronization of the gear wheels prior to engaging a higher gear, for which purpose a two-part interceptor slide disposed between the rotor and the stator is arranged to be operated in conjunction with means for controlling the filling of the brake, by either a single operating member or a plurality of interlocking operating members, so that the brake is emptied when the slide is inserted and the slide is fully withdrawn when the brake is being filled. In one embodiment, Fig. 1, a motor 2 is coupled to driving shaft 4 on which are keyed gear-wheels 5, 6. Gear-wheels 7, 8 mesh respectively with the gear-wheels 5, 6 and are loose on a driven shaft 9, one or other of the wheels 7, 8 being coupled to the shaft 9 by a sliding clutch sleeve 10 having dog teeth 13, 15 for mating respectively with dog teeth 12, 14 on the wheels 7, 8. A hydrodynamic brake is arranged with its rotor 18 secured to driving shaft 4 and interceptor slides 20, 21 (see also Fig. 2), shaped and arranged for movement by rotation of a shaft 22 having threads of opposite hand, in the manner described in the parent Specification to prevent flow of air between the vanes of the rotor 18 and those of the stator 19 when braking is not required, thus preventing winding losses. When the gearing is to be changed from low to high gear, control measn is operated which first disengages the low gear, then causes the slides 20, 21 to be withdrawn, fills the brake with liquid to a level determined by the degree of braking required, and when synchronization is obtained empties the brake, shuts the slides 20, 21, and engages the higher gear. The control means comprises a first operating lever 11 for moving the sleeve 10 and a second operating lever 39 for controlling, via a cam disc 40, a control valve 42 determining the filling speed of the brake. Lever 11 also operates a disc 31 for controlling a reversing switch 29 (see also Fig. 2) for the motor 25 which moves the plates 20, 21. Discs 31, 40 are interlocked by a rod 45 so that lever 11 must be in the 0-position (neutral) before lever 39 can be moved from its 0-position to apply the brake and, vice versa, the brake must be released prior to engagement of the higher gear by moving lever 11 to position II. As shown in Fig. 2, the reversing switch 29 controls a three-phase supply, in conjunction with limit switches 36, 37 actuated by plate 21 in its outer and inner limiting positions, respectively, so that when switch 29 reverses the plates 20, 21 move to their opposite limiting positions and stop. In Fig. 2, a single lever 53 replaces the levers 11, 39, engaging the gears at positions I, II and applying the brake progressively, through cam disc 54, over positions 1-3. Disc 54 progressively moves a piston 56 of the valve 42 to vary the flow from a pump 57 via pipe 43 to the brake, the return being at a fixed rate via pipe 59. During such braking plates 20, 21 are opened since plunger 30 of switch 29 is in recess 55a of cam disc 55 which rotates with disc 54. Piston 56 returns to cut the supply of braking fluid as lever 53 is moved to position II, switch 29 at the same time reversing to close together plates 20, 21. In the embodiment of Fig. 3, motor 65 is coupled to driving shaft 67 which drives driven shaft 76 through either gear-wheels 68, 73 or 69, 74 according to whether or not a free-wheel clutch 71 is engaged, a free-wheel clutch 70 being permanently operative. A single operating lever 78 is used to control, through cam discs 79, 80, the valve 42 and reversing switch 29, respectively. A further cam disc 81 controls freewheel clutch 71 through link 82 and lever 72. In this embodiment only one degree of braking is provided, selected at position B intermediate positions I and II. In operation, shaft 67 is braked to a slightly slower speed than necessary and free-wheel clutch 71 is then engaged and takes up the drive as the speed of shaft 67 is again increased by the motor 65.