Patent GB-591114-A (GB)
Title: Improvements in or relating to variable speed gears
IPC: F16H61/02
Filed: 1945-01-18
Abstract: 591,114. Variable-speed epicyclic gearing; friction clutches and couplings. LOMBARDINI, P. C. Jan. 18, 1945, No. 1499. [Class 80 (ii)] In a sun-planet-annulus epicyclic gearing having a mechanically or hydraulically controlled clutch of the type described in Specification 587,651 coupled between the driving sun and one of the other gearing members, the remaining member being driven, the drive is locked solid up to a predetermined maximum torque beyond which the clutch slips giving reduced speed ratios. As shown in Fig. 1 the gear is combined with a second similar gear, pre-selector means being provided to operate brakes holding one or other of the annuli against rotation and to disengage the clutch to give a fixed ratio reduction or a reversed drive. The hollow input shaft 3 carries both the driving sun 12 and the floating pressure ring 4 of the clutch whose outer member 28 is freely mounted on the shaft 3 and is rigid with the annulus 19 journalled on the planet carrier sleeve 14a which is splined on the output sleeve 13 journalled on an extension 3a of the shaft 3. The planet carrier sleeve 21a of the second gear is also splined on the output sleeve 13, its sun 19c, which is slightly larger than the sun 12, being connected to the annulus 19 and its annulus 23, which is the same size as the annulus 19, being journalled on the sleeve 21a. The clutch is operated mechanically through a spring-pressed plunger 5, working in the bore of the input shaft 3, which co-operates with a single sliding pressure rod 7 resiliently linked to the pressure ring 4 and is operated by a central rod 8 abutting against a pad 9 rigid with the yoke 11 and forked lever 10 of the clutch operating assembly. The clutch may be hydraulically operated, the hollow of the input shaft being connected to a source of liquid whose pressure can be suitably controlled and which acts on a plunger formed by the end of the pressure rod. A variable speed coupling is shown in Fig. 8, there being no manual clutch operating means and no reverse epicyclic gearing. The load at which the coupling slips is predetermined by the initial compression of the spring 41 which may be adjustable as by a nut 39. In Figs. 2 and 3 the preselector means referred to above are shown. Each of four axially spaced cams 43-46 operated by a lever 47 can be turned to depress the corresponding one of four spring plungers 48 to move one of four selector struts such as 49, 51 downwards against its return spring 68 to engage a bus bar 53 when the latter is rocked on its pivot 54 by the disengaging movement of the main clutch pedal 67 acting through the link 58 and lever 57, the previously engaged strut simultaneously disengaging under the action of its spring 68. The two selector struts corresponding to the annuli brakes are mounted on brake operating levers 52, Fig. 3, so that when either has been engaged with the bus bar the return movement of the main clutch pedal 67 allows a brake spring 55 connected to the bus bar to act thereon and apply the appropriate brake. Two further selector struts corresponding to neutral and variable speed working are mounted on fixed pivots, Fig. 2, so that when they engage the bus bar the spring 55 remains compressed on the return movement of the pedal 67 and the annuli are left free. The neutral and braking selector struts only each possess a finger such as 49a, 51a which when they engage the bus bar act through a system of bell-crank levers 59, 61, 63, 64, 65, Fig. 2, to throw a snap-detent 66 into the path of the clutch operating yoke 11 preventing it from re-engaging the clutch after the clutch pedal 67 has been depressed and released to bring in the gear.