Patent GB-681010-A (GB)
Title: Improvements in or relating to change-speed gears
Filed: 1949-08-08
Abstract: 681,010. Change-speed gear. HUMBER, Ltd., and KAMPER, A. M. Oct. 26, 1950 [Aug. 8, 1949], No. 20631/49. Class 80 (ii). Main electromagnetic friction clutches B, A selectively drive a countershaft 110 at either of two ratios through the nested concentric shafts of low and second-speed pinions 1, 3, at least one further ratio (two shown) being provided mechanically, as by a friction or balksynchronised double-dog clutch 113, operated by a reversible electric motor 3a, Fig. 2. As shown the four forward ratios and neutral are controlled by individual push-buttons N, 1, 2, 3, 4, mechanically interconnected so that depression of one automatically releases any y other. For reverse a lever X, Fig. 2, moved manually through a cable, mechanically slides an idler to mesh teeth 7, 9. With the dog-clutch 113 in its rear position the output shaft 112 is clutched to a wheel 5 and driven from the input 100 in first and second ratios through the clutches B or A, wheel pairs 1, 2 or 3, 4 and 6, 5. Moved to the forward position the dogclutch 113 provides third and high speed respectively through the clutches B, or A, wheelpairs 1, 2, 4, 3; and directdrive. The selective push-buttons N -4 energise relays a-f acting as follows. Relays d e control operation and direction of the dog-clutch shift-motor 3a by feeding respectively upshift and downshift field-windings H, L in series with the motor armature 3a, which is also in series with the relay f, energisation of which, coincidentally with that of the armature, energises a clutch 39 through which the motor drives the shift-crank of the dog-clutch 113, and simultaneously cuts out current-feed to the main clutches A, B, which are thus always disengaged during a shift of the dog-clutch. Feed from the contacts of the de-energised relay f to the main clutches A, B is through the contacts of two relays a, c, which, when both disengaged, feed clutch A only, whilst when a is energised alone, in first speed, or c alone in third, feed is to clutch B only. Relay b is energised for neutral, position shown. The dog-clutch shiftmotor 3a drives an arm 34 having earthed contacts 33 moving over contact-strips 30 &c., to form circuit preparing and limit switches which break circuit at the end of a shift and prepare for the next opposite shift. For this purpose the two motor-control relays d, e are connected through one set of the double change-over contacts of the neutralising relay b, in its energised position, shown, to opposite limit-switch contacts 32, 32a respectively, so that depending on whether the shift into neutral is made from high or low gear position of the shift motor arm 34, the appropriate low or high shift-motor relay e or d is energised through the contact 32a or 32 respectively, the circuit being broken in the mid position. Limit-switch contact-strips 30, 31 act similarly in conjunction with the other set of contacts of the neutralising relay b in its de-energised position, to determine the direction of motor-rotation and final circuit-break for direct shifts between low and high gear positions of the dog-clutch motor 3a. The reverse switch-arm X carries earthing contacts 120 which, in the reverse position, cause energisation of relay b, neutralising the dog-clutch 113 .and also of relay a selecting the low-speed mainclutch B. The main-clutch supply line (so marked) is fed initially by a motor-driven generator, with subsequent change-over to battery-feed, as described in Specifications 610,519 and 635,792, and may include a fast idler as in Specification 610,593. The clutches A, B comprise single driven discs 105, 106 clamped selectively to an axially-fixed centre drive-disc 104 by presserplate armatures 102 secured together by bolts 103 to form a unit which is moved in the appropriate direction for engagement of either clutch by energising opposed windings 101. The clutches A, B embody features of Specifications 610,594, [Group XXXV], 610,595, 645,700 and 645,728. The dog-clutch shift-motor 3a is bolted externally to the gear-casing and drives, through a planetary gear and clutch 39, a crank projecting into the casing to engage the clutch shift-yoke 200, as described in Specification 632,028. Specification 594,906 also is referred to.