Patent GB-726227-A (GB)
Title: Improvements in and relating to gear-changing devices
IPC: B60K17/346
Filed: 1953-02-24
Abstract: 726,227. Controlling change-speed and differential gearing. MASCHINENFABRIK AUGSBERG-NURNBERG AKT.-GES. Feb. 24, 1953 [Feb. 27, 1952], No. 5170/53. Class 80 (2). A gear changing device, for use in powered vehicles in which drive is transmitted to all the .wheels and provided with a number of control members operating different units, is characterized in that, while the change-speed lever of the ordinary change-speed gear is retained, the control of a transfer gear, giving two ratios suitable for either road work or cross-country running and containing a differential which is locked to drive both front and rear axles, is effected by the operation of press-buttons. In the form shown, a press-button 1, Fig. 1, connects a pipe 11 supplied with compressed air through a valve 11a to a pipe 12 and piston actuated mechanism 14 which slides a sleeve 33, Fig. 6, in the transfer box to connect one of two gears 36, 41 to a driving shaft 39, and a press-button 1a, Fig. 1, similarly allows compressed air to be supplied through a pipe 47 to a second piston actuated mechanism 49 which can slide a sleeve 62 to lock the differential. The press-buttons each comprise a body portion 2, Fig. 2, in which are a button 5 and a valve 3 urged to the closed position by springs 10, 6, and plunger 4 actuatable by the button to open the valve and connect inlet and outlet passages 8, 9, an escape passage 42 being connected to the outlet 9 when the valve is closed. The change-speed actuator 14 consists of a piston 17, Fig. 3, in a cylinder 16, a rod 19 having a flat head 19a engaging at one side a round-headed bolt 20 in the piston and at the other one end of a compression spring 21 whose other end abuts bars 22 in the cylinder case. A rocking element 24 is secured to a shaft 25 connected to a snap-over device, Fig. 4 (not shown), externally of the case, which holds the rocking element in one or other of its two extreme positions, corresponding to whether the cross-country or road ratio is established in the transfer box, the shaft 25 being mechanically connected to the sleeve 33. In the position shown in Fig. 3, compressed air has been admitted through the press button 1 to the cylinder 16 and the rod 19 is engaged with a notch 23 in the rocking element 24, which has thus been moved in the anti-clockwise direction to engage the road ratio. On release of the press-button 1 pressure in the cylinder 16 is released and the spring 21 moves the piston 17 and rod 19 downwardly, the rocking element 24 staying in the position shown due to the snap-over mechanism actuated by the shaft 25. When compressed air is again admitted to the cylinder 16, the rod 19 is moved upwards to engage with a face 45 of the rocking element along which it slides into a notch 23a to move the rocking element 24 in the clockwise direction and move the sleeve 33 axially, first to disengage the road ratio and then engage the cross-country ratio (gear 41) in the transfer box. The snap-over device connected to the shaft 25 works an electric switch controlling the supply of current to an electric lamp which is lit up when the cross-country ratio is engaged. The actuating device 49 for the differential lock comprises a piston in a cylinder, Fig. 5 (not shown) connected through springs and links to a pivoted lever 59, Fig. 6, abutting the end 61 of the sleeve 62 which has external teeth 65 engageable with teeth 66 on the casing 67 of the differential to lock the latter.