GB851591A - Automatic gear-changing apparatus for road, rail or other vehicles - Google Patents

Abstract

851,591. Change-speed gearing. C.A.V. Ltd. Oct. 25, 1956 [Oct. 26, 1955], No. 30590/55. Class 80 (2). In electrically - operated gear - changing apparatus controlled automatically by vehicle speed, means are provided to bring all the gears to neutral position in the event of failure of the speed-responsive device whilst at least the highest of the ratios is engaged. As shown, first speed is engaged upon closing a switch n2 by energisation of a magnet 1 from a battery c through closed switches n<SP>1</SP>, ml, d<SP>2</SP>, e<SP>3</SP>, f<SP>4</SP>. Higher speeds are brought in as vehicle speed increases by a vehicle generator a which successively closes relay switches g<SP>1</SP>, h<SP>1</SP>, j<SP>1</SP> to energise the coils d, e, f of contactors associated with magnets 2, 3, 4 for these higher speeds. Contacter d serves to open switch d<SP>2</SP>, de-energising magnet 1, and close a switch d<SP>1</SP>, energising magnet 2 through closed switches e2, f<SP>3</SP>, Contactor e serves to open switches e<SP>2</SP>, e<SP>3</SP>, deenergising magnet 2, and close a switch el, energising magnet 3 through closed switch #<SP>2</SP>. Contactor f serves to open switches f<SP>2</SP> f<SP>3</SP>,f<SP>4</SP>, deenergising magnet 3, and close switch #<SP>1</SP>, energising magnet 4. In the arrangement shown in Fig. 2, the primary winding of a transient current transformer p is connected in series with the generator a and the secondary winding is connected in series with a relay winding o<SP>1</SP>. In the event of failure of the speed-responsive system, the sudden cessation of current through the primary winding of transformer p produces a transient current in the secondary winding which passes through the relay winding o<SP>1</SP>, causing a switch o<SP>3</SP> to close and switch o<SP>4</SP> to open, so bringing all the gears to neutral. Closing of switch o<SP>3</SP> brings a holding winding o<SP>2</SP> into action for holding the switch o<SP>4</SP> open. In the arrangement shown in Fig. 3, the generator a, or alternator plus rectifier, closes a relay switch q<SP>1</SP> to energise a delayed-action magnet k operative to close a normally-open switch k<SP>1</SP> in series with a normally-closed switch d3, opened by coil d, and a coil m controlling a switch m<SP>1</SP> (equivalent to o<SP>4</SP>, Fig. 2) and normallyopen hold-on contacts m<SP>2</SP> in parallel with the switches d<SP>3</SP>, kl. In the event of failure of the speed-responsive system, switch d<SP>3</SP> closes and, due to the delay action of magnet k, switch k<SP>1</SP> remains closed sufficiently long for coil m to open switch m<SP>1</SP>, and close switch m<SP>2</SP>, which latter then maintains coil m energised. In Fig. 1, not shown, the relay switch q<SP>1</SP> is replaced by a pair of switches in parallel, these being closed respectively by the contactors e and f, so that the apparatus functions as in Fig. 3 only when in third or fourth speed.