GB1439589A - Motor vehicle drive system - Google Patents

Abstract

1439589 Change-speed gear GKN TRANSMISSIONS Ltd 27 Nov 1973 [29 Nov 1972] 55199/72 Heading F2D An auxiliary over- or under-drive two-speed gear 11, arranged behind a main change-speed gear 10 controlled solely by a manual shift lever 13 on a motor-vehicle, is alternately upshifted and downshifted solely by repeated depressions of the usual main clutch pedal after the highest ratio has been established in the main gear. Because of the essential clutch disengagement the auxiliary gear is therefore never shifted under load, and this permits the use of smaller friction clutch-brakes or of synchromeshed positive ones. The control also ensures that the auxiliary gear is in low before the highest ratio is established in the main gear. Gear arrangement.-The auxiliary gear shown provides direct drive between input and output shafts 16, 21 when a diaphragm spring 30 shifts right, through a thrust bearing 26a, a clutchbrake cone 26 to clutch frictionally a freely mounted sun 17 to an input-mounted planet carrier 19, which latter is additionally connected to output 21 through a one-way clutch 19a. Pressurizing a cylinder 34 shifts left a piston 33, acting through a thrust bearing 36 on the clutchbrake cone 26 to release it from the planet carrier 19 and engage it with a stationary brake surface 37, thus holding the sun to overdrive a ring gear 20 fast with the output shaft 21. fluid pressure system.-A piston pump 40, reciprocated by an input-mounted eccentric 38, supplies liquid pressure direct to the clutchbrake cylinder 34, under control of a pressure relief valve (43, Fig. 2, not shown) and a normally exhausting ball valve (44), closure of which, by energization of a solenoid 45, causes pressure to build upon the cylinder 34 to produce upshift. Electrical control system.-Energization of the shift-valve solenoid 45 from a current source 46 is effected through a relay 48, controlled by a switch 47, closed only when the highest ratio is established in the main gear, a switch 64 closed by pressure in the shift cylinder 34, and a doublepole switch 60 closed by depression of the main clutch pedal. Starting from the low ratio condition shown, establishment of the highest ratio in the main gear closes the switch 47 supplying current, without effect, to the relay armature 50. Subsequent momentary depression of the clutch pedal pulses the switch 60, upper contacts 59 of which energize the relay coil 53 through a line 58 and ballast resistor 54. The armature then closes contacts 51 and 52 to 56, 55, the latter, 55, completing a hold circuit for the relay coil, the former, 56, energizing the valve solenoid 45 for upshift, which is signalled by a lamp 65. Upshift causes the pressure switch 64 to close, without effect since the clutch switch 60 has been re-opened by release of the clutch pedal. The next depression of the clutch pedal again pulses the switch 60, the lower contacts 62 of which, through the nowclosed pressure switch 64, earth both ends of the relay coil 53 through the ballast resistor 54, permitting the contact 51, 56 to open and deenergize the valve solenoid 45, producing downshift. Hydraulic, pneumatic, or suction sensors may replace the electric ones.