GB730424A - Improvements in or relating to self-changing gearboxes - Google Patents

Abstract

730,424. Change-speed gearing. SMITH, A. P. Nov. 18, 1953 [Feb. 28, 1953], No. 5680/53. Class 80 (2). A miniature gear box 11 having the same gear ratios as the constant-mesh clutch-operated main gear box 1 has its output shaft 16 geared at 17 to the output shaft 10 of box 1 while its input shaft 18 carries a permanent magnet 19 co-operating with a soft-iron member 21 mounted with limited spring-resisted lost motion on a shaft 20 geared at 23 to the input shaft 4 of box 1. Shaft 16 is moved axially to engage a selected new gear in box 11 and, with a slight lag due to springs 32, to move a contact arm 30 from a contact stud 31 corresponding to the previously-engaged main gear on to a new stud corresponding to the selected new main gear, so that, by the action of magnet 19 on member 21, normally-closed contacts 22, 24 connected to slip rings 27, 28 are first opened to break the circuit through a solenoid 6 whereby the previously-engaged gear clutch 5 in box 1 disengages. The circuit through the solenoid of the newly-selected main gear is not completed until the engine speed has been adjusted to bring the shafts 18, 20 into synchronism, enabling the contacts 22, 24 to close again. As shown, this adjustment is automatic, there being additional contacts 45 one or other of which engages the contact 22, when the latter disengages from the contact 24, so as to energize one or other of two solenoids 47 acting to open or close the throttle 49, which is connected to the accelerator pedal 51 through springs 52. Shaft 16 may be controlled manually, or, as shown, by a centrifugal governor 44 driven by shaft 16. In this case, the pedal 51 may act through a liner 53 to increase the spring loading of the governor when the pedal is depressed. Alternatively, the relative movement between shaft 20 and member 21 may open and close ports in a pneumatic or hydraulic pipe system operating the clutches 5.