Patent GB-497578-A (GB)
Title: Improvements in or relating to change-speed gearing
IPC: F16H61/02
Filed: 1937-04-15
Abstract: 497,578. Change-speed and reversing gearing. BRAMBLE, W. H., and RUSTON & HORNSBY, Ltd. April 15, 1937, No. 10705. [Class 80 (ii)] Change-speed gearing of the kind comprising hydraulically-actuated double friction clutches A, B, C, D, arranged between the loose wheels of constant-mesh pairs on parallel shafts, is controlled by a hollow rotary cylindrical distributing-valve 29, Fig. 4, having separate inlet and exhaust ports for each clutch, adapted to register with separate single casing-ports for each clutch. The valve-casing 27 also has a coaxial rotary cylindrical valve 30, controlling a hydraulicallyactuated main-clutch, or forward and reverse main-clutches, the valve 30 being interlocked mechanically with the speed-changing valve 29 in the manner described below. The gearing shown provides four speeds in either direction and comprises two two-speed gears arranged in series between a driving shaft 12, Fig. 2, and a parallel driven shaft 14. An intermediate shaft 13 is driven at either of two speeds from the driving shaft 12 according as either of two hydraulically-actuated friction clutches A or B are engaged to introduce wheel-pairs 129, 131 or 130, 132. Similarly the driven shaft 14 is driven at either of two speeds from the intermediate shaft 13 according as the clutches C or D introduce trains 133, 135 or 134, 136 respectively. A wheel-pair 137, 138 connects the shaft 14 to the final driven shaft 96, having sprockets 139, connected by chains to a locomotive axle. The driving shaft 12 is driven through either a single hydraulically-actuated main-clutch, or through forward-neutral-reverse gearing comprising a bevel 128 fast on the shaft 12 and engaging bevels 108, 108a, Fig. 3, loosely mounted on a main driving shaft 99, and clutched thereto by hydraulically-actuated main friction-clutches 98, 97 respectively. The clutches 98, 97 each comprise frictionfaced splined plates 101 between the bevels 108, 108a and housings 98, 97 fast on the main driving shaft 99, the clutches being engaged against springs 110 by direct-acting pistons 115, carried in the rotating housings 98, 97 and subjected to oil-pressure through ports 116, leading through shaft-borings 120, 120a, annular spaces 122, 122a in a fixed member 123, and pipes 124, 124a to the forwardneutral-reverse rotary distributing-valve 30, Fig. 4, described below. The change-speed clutch-pair A, B, which is the same as C, D, is of the form described in Specification 497,575, and comprises internally coned friction-lined driving clutch-elements A, B, integral with the wheels 131, 132 respectively. A cooperating double-coned clutch-element 17 is connected by bolts, not shown, to rotate with, but have axial freedom relative to a driven member 20, fixed on the shaft 13, and formed with oppositely directed cylinders housing pistons 24, abutting against opposite internal walls of the double clutch-cone 17. Supply of oil-pressure to one set of pistons 24 and simultaneous exhausting of the oppositely-directed set, causes the double-cone 17 to move in the appropriate direction to engage one or other of the clutch-cones A or B and simultaneously disengage the other. This disengagement of the clutch A or B not required is positive and does not require spring-assistance. Oil-pressure reaches the pistons of the clutches A, B, C, D by way of shaft-borings 22a, 23a, annular grooves 22d, 23d in the shafts and pipes 22A, 23B, 22C, 23D, leading to ports A<0>, B<0>, C<0>, D<0>, Fig. 5, of the manual rotary distributing-valve 29, Fig. 4. The speedchanging distributing-valve 29 and the forwardneutral-reverse or main-clutch distributing- valve 30 are arranged with their ends adjacent each other in the same valve-body 27. The speed-changing valve 29 has two rows of ports, one row 1<2>D &c., controlling the clutches C, D through the oppositely arranged ports C<0>, D<0>, Fig. 5, whilst the other 1<1>B, &c. controls the clutches A, B, through the ports A<0>, B<0>. Each row comprises radial through-ports, e.g. 1<2>D, communicating with exhaust 143, through communicating central borings 29a, 30a, in the speed-changing valve 29, and the reversing-valve 30, and a radial boring 142 and annular groove 30e in the reversing- valve 30. Alternating in a desired sequence with the through-ports 1<2>D &c. are surfaceports 32D, &c., leading to an annular groove 29e, communicating with a main pressureinlet 28. The ports are spaced 36‹ apart and the arrangement is such that, as the speed-changing valve is turned through steps of 36‹, different combinations of the clutch pairs A, B and C, D are selectively energized whilst remaining pairs are exhausted. The valve 29 has five positions, corresponding to each of four speeds and neutral, in which latter position all four clutches A, B, C, D, are exhausted. The reversing or main-clutch valve 30 has two opposed through-ports 145, leading to exhaust 143 through the central boring 30a, and a single arcuate surface-port 144, communicating, in all positions of the valve, with a pressure-port 36. A pipe-connection 147, Fig. 5, leads to the control-pipe 124a, Fig. 3, of the forward main-clutch 97, whilst another pipe-connection, (not shown in Figs. 4 or 5), on the opposite side, leads to the control pipe 124 of the reverse mainclutch 98, the arrangement being such that in a central region of movement of the valve 30, both clutches 97, 98 are exhausted, whilst positions to either side of this region energize the forward-clutch 97 and exhaust the reverseclutch 98, or vice versa. For providing a degree of slip in the main-clutch or clutches 97, 98, the pressure-port 36, Figs. 4 and 5, of the reversing-valve 30, derives its pressure from ports 31, 32, in permanent connection with the main pressure-inlet 28, the port 32 leading to the port 36 through an adjustablyspring-loaded pressure-reducing valve 37 and a port 33. Bye-passing this reducing-valve 37 is an adjustable throttling-valve 45, the arrangement being such that the main-clutch or clutches 97, or 98 are first engaged under light pressure through the reducing-valve 37, the pressure building up to the full inletpressure at 28 after a period determined by the setting of the throttling-valve 45. This pressure-control of the main-clutch or clutches forms the subject-matter of Specification 497,576. -The speed-changing and reversing or main-clutch valves 29, 30 are mechanically interlocked in such a manner that the speedchanging valve 30 cannot be moved until the reversing-valve 29 has been set in neutral and the reversing-valve cannot be moved from forward to reverse, or vice versa, or to engaged position in the case of a single mainclutch, unless the speed-changing valve has been set in neutral. For this purpose there is an interlocking bar 167, urged by a spring 168 into engagement with any one of five notches S<2>, circumferentially arranged on the face of an arm 141, secured to the valve 29, so as to define neutral and gear positions of the valve. The opposite end of the interlocking bar 167 co-operates with an arm 140, fixed to the reversing or main-clutch valve 30, the arm 140 being provided with an arcuate groove 169 in its central neutral region, so that it is only when the reversing-valve is in neutral that the interlocking bar can move to the left sufficiently to leave a notch S<2>, whereby movement of the speed-changing valve 29 is positively prevented in all positions, other than neutral, of the reversing-valve. Centrally disposed on the arm 140 is a pin 170, which, in all speed-positions of the valve 29 is obstructed by the end of the interlocking bar 167, so that it is not possible to move the reversing-valve 29 past its central position in either direction. The notch N for neutral on the arm 141 of the speed-changing valve, is deeper than the other notches - S<2>, so that only when the speed-changing valve is set to neutral does the interlocking bar 167 move out of the path of the pin 170 and permit the reversing-arm 140 to be moved past its central position from forward to reverse, or vice versa. In the exact central position of the reversing-arm 140, its pin 170 overlies the interlocking bar 167 and prevents the speedchanging arm 141 from being moved out of the neutral position. This is deemed a " safety position." The reversing-arm 140 has five positions in each of which it is retained by a spring pressed detent-bar 163, the positions corresponding to forward, reverse, central " safety position, neutral-forward and neutralreverse, the last two positions lying on either side of the safety position, but still within the central neutral zone of the reversing- valve. The speed-changing and reversing valves are controlled by separate levers, the reversing-valve being operated by either of a pair of levers 150, 150a, Fig. 14, arranged conveniently at opposite sides of the locomotive, and secured on a shaft 158, directly linked at 149 to the arm 140 of the reversing-valve. A single centrally disposed speed-changing lever 156, freely mounted on the shaft 158, operates the spindle of the speed-changing valve 29 through a rod 151a, and rack-andpinion 151, 153. Indicating quadrants and pointers, as shown, are provided for all the levers. The hydraulic pressure for the clutches is produced by a pump 65, Figs. 10 and 11, in conjunction with an accumulator 78, which initially is supplied with pressure air or gas, as well as oil, to result in a cushioned pressure. For this purpose a three-way cock 79 is arranged in the pipe 77, leading from the delivery-chamber 74 of the pump to the accumulator 78, and the line (not shown) leading to the main pressure-inlet 28, Fig. 4, of the clutch-controlling distributing-valves. Initially the cock 79 is turned to cut off the pressure-inlet 28 from both pump and accumulator and an air-admission cock 95 is opened on the suction side of the pump 65, which thereupon pumps air to the accumulator 78. When the desired pressure i