Patent GB-563963-A (GB)
Title: Improvements in or relating to change-speed gears
IPC: F16H3/091
Filed: 1943-03-02
Abstract: 563,963. Variable - speed gearing. SHELLEY, T., and ROBINSON, N. R. March 2, 1943, No. 3438. [Class 80 (ii)] In a three-speed gear, gears 14, 15, driven by a moderate-speed friction clutch mesh with gears 22, 26, to give medium and low speeds respectively to a driven shaft 18, the gears 22, 26 being connected to the shaft 18 by a synchrocoupling of the Legge type, e.g. such as described in Specification 354,711. A gear 16 driven by a high-speed friction-clutch meshes with a gear 17 splined to the shaft 18. The two friction-clutches are mounted within a casing 13 on a countershaft, and are controlled hydraulically by a valve 46, Fig. 3. The gears 22, 26, nested one within the other, have dogs 25, 31, engageable with dogs 34 and pawls 35, 36, all on a sleeve 32 splined helically to the high speed gear 17. A coupling locking-member 37 is splined at 38 to the sleeve 32 and has dogs 39 engageable with dogs 40 on the pinion 17. The locking member 37 can be slid axially on the sleeve 32 by actuation of a gear selector-lever 42 connected thereto by links 43, 45, 44, Fig. 3. Link 43 is connected to a lever 47 pivoted at 48 and engaging the spring-controlled member of a valve 46 for actuating the high and moderate speed friction clutches, the engagements of which occur when the spring - controlled member is in its innermost and outermost positions respectively. When the, lever 42 is in its low-speed position, Fig. 3, both locking member 37 and sleeve 32 are in their right-hand positions, Fig. 1 (not shown), the dogs 39, 40 are disengaged, the moderate speed friction clutch is engaged, and the dogs 34, 31 are engaged. Drive is therefore transmitted from the low speed gear 15 through the members 26, 31, 34, and sleeve 32, through the helical splines to the high speed gear 17 and thence to the shaft 18. To obtain medium gear ratio, the lever 42 is moved anticlockwise, Fig. 4 (not shown). The locking-member 37 cannot be moved as the dogs 39 are blocked by the dogs 40. The link 43 is thus rocked to actuate the valve 46 to engage the high speed clutch and disengage the moderate speed clutch. Pinion 17 then speeds up and when it overruns the sleeve 32, the latter moves to the left, Fig. 2, until the dogs 34 lie between the dogs 25, 31. When the shaft 18 attains a speed equal to the gear 22, the pawls 35 engage the dogs 25 and further increase of speed of the shaft 18 causes final movement of the sleeve 32 to the left so that the dogs 34 engage the dogs 25. The dogs 39, 40 are now aligned so that the spring of the valve 46 expands to rock the link 43 to cause axial movement of the member 37 and at the same time engage the moderate speed friction clutch and disengage the high-speed clutch. The shaft is then driven from the medium speed gear 22 and the parts' are positioned as in Fig. 2. For third speed the lever 42 is moved further anticlockwise, Fig. 6 (not shown), so as to engage the high speed clutch and disengage the moderate speed clutch. During this speed, the gear 22 runs idly. The friction clutches may be controlled by means such as described in Specification 551,002. The invention may be applied to drive an aero engine supercharger.