Patent GB-112546-A (GB)
Title: Improvements in Means for Controlling the Operation of Power Transmission Clutches and the like.
Inventor: WEBB WILLIAM HUBERT
IPC: F15B15/22
Filed: 1917-03-09
Abstract: 112,546. Webb, W. H. March 9, 1917. Controlling clutches &c.-Relates to dash-pot devices for assuring the rapid movement of the parts of clutches or like machine elements into contact and the slow subsequent increase of engaging-pressure. Figs. 1 and 5 show the position of the parts when the clutch parts 27, 28 are in full engagement. The pedal-shaft 25 carries an arm 26 connected to the end 6 of a rod 5 passing into a cylinder 1, containing oil, air, or other fluid, and abutting against a slide 3 between which and a piston 2 is arranged a strong compression spring 4 keeping in compression a .veak spring 9 below the piston. A valve 12 controlling parts 11 is normally pressed upwards by a spring 13 and contains a plug valve 14 pressed upon its port 15 by a spring 16. When the clutch is disengaged against the action of springs 30, 33, the rod 5 is lifted and the spring 9 lifts the parts 2, 3, 4 until the slide 3 engages an adjustable stop 8 or the cylinder top, oil passing by a valve 12. On releasing the pedal, the springs 30, 33 return the rod 5, compressing the spring 4 against the stationary piston 2 until the pressure of the spring 4 balances that of the spring 30, in which position the clutch surfaces are just in contact and the spring 33 is fully contracted. Oil then escapes slowly from below the piston 2 through the valve 14, thus relieving the compression of the spring 4 and allowing the spring 30 to come into action, until the spring 16 is able to close the valve, when the remainder of the pressure below the piston is relieved by leakage past the various parts or by the use of a suitable by-pass. In order to allow for a rapid tightening of the clutches after the drive has been fully taken up, the valve 14 may engage a port in a loose disk supported in the value 12 by fluid pressure until the pressure below the piston 2 falls sufficiently, when the disk falls and the oil escapes freely. A rounded end 19 on the cylinder 1 allows for the necessary rocking of the cylinder. The value 14 may be replaced by a by-pass 86, Fig. 11, controlled by an adjustable ball valve 84, the end of the by-pass 84 being closed when the piston 72 falls and the slow leakage taking place through a by-pass 94, the end of which is uncovered by the fall of the piston to allow final rapid release of the oil. The by-pass 94 may be replaced by a passage opening above the piston 2 and normally closed by a valve, which is opened automatically when the fall of pressure below the piston 2 reaches the last stage. Fig. 8 shows the application to operating-gear in which the rod 45 rises for clutch engagement. The rod is secured to the cylinder 41 which moves in a cylinder 61 sliding in the framing 60 and bearing against forks 65 secured to the slide 43. A groove 62 allows passage of oil from the top to the bottom of the cylinder 61. In this form, the pressure of the spring 44 is conveyed to the rod 45 through the cylinder 41 and the oil below the piston 42. In all forms, the spring 4 may be replaced by an air cushion in the upper part of the cylinder or of a separate cylinder, a rigid connexion conveying the pressure to the piston. The weak spring 9, &c., may be dispensed with by attaching the two ends of the spring 4 to the piston and slide respectively and connecting the rod and the slide by a spring connexion. According to Provisional Specification 3463/17, a pistonrod connected with lost motion to the clutch gear is provided with a flange arranged inside a hollow piston, the main spring being placed between the flange and the bottom of the piston. The piston may carry a small relief valve provided with a pin which strikes the bottom of the cylinder and opens the valve, so that the piston may have an increased speed at the beginning of its rise.