Patent GB-800325-A (GB)
Title: Improvements in valve mechanisms
IPC: F16K31/06
Filed: 1955-09-15
Abstract: 800,325. Controlling change-speed gearing. BENDIX AVIATION CORPORATION. Sept. 15, 1955 [Sept. 16, 1954], No. 26464/54. Class 80 (2). [Also in Group XXIX]  A two-speed axle-overdrive or other gear or a reversing gear of a motor vehicle is operated by a double-acting engine-suction servomotor 12, Fig. 4, controlled by a four-way valve mechanism 40, Figs. 2 and 4, operated by a pair of solenoids 84, 114 each having a pulling coil and a weaker holding coil, the switching means being such that when either solenoid is operated both of its coils are energized but, at the completion of the armature movement, its pulling coil is de-energized while its holding coil remains energized. The solenoids control valves 90 which put conduits 54, 58, leading to the underside 56 and to the upper side 59 of the servo diaphragm 16, alternatively into communication with atmosphere at 50 or with a conduit 60 connected to the engine intake manifold. The servo 12 comprises the diaphragm 16 connected to a rod 28, a slidable gear-operating rod 20, and a spring 30 between abutments 32, 34 loose within a tubular extension 24 of rod 20, the abutment 32 normally resting against a part 22 of rod 20 and against a nut 36 on rod 28 while the abutment 34 normally rests against a stop ring 25 in the extension 24 and against a part 38 of diaphragm 16. In the form shown in Fig. 2, the solenoids are energized alternatively by a manual two-way switch, and a flexible contact strip 110 is moved by a pin 112 operated by the armature 86 to break the circuit of the pulling coil at the end of the armature movement. If, with the vehicle travelling in low gear with solenoid 114 energized and diaphragm 16 in the position shown, the manual control switch is thrown over to high-gear position, deenergizing solenoid 114 and energizing solenoid 84, the valves 90 move to vent servo-chamber 59 to atmosphere and connect chamber 56 to engine suction. Diaphragm 16 thus moves downward, compressing spring 30 with rod 20 remaining stationary until the accelerator is released to enable the low-speed gears to disengage. The high-speed gears then engage when synchronism is attained. In the form of switch control shown in Figs. 4 and 6, in which the contact strip 110 is dispensed with, a manually slidable switch member 142 co-operates with contacts 138, 140 connected to a battery 98, contacts 130, 136 connected to the two pulling coils, and contacts 132, 134 connected to the two holding coils. On moving member 142 to one extreme position by a knob 152, contacts 130, 132 (or 136, 134) are both connected to contact 138 (or 140) to energize both coils of the appropriate solenoid. On releasing knob 152, a spring 162 (or 170) acts to move member 142 back a little to disengage it from contact 130 (or 136) so as to de-energize the pulling coil, and the member 142 is held in this position by a spring-loaded ball detent 156 engaging a recess 158 (or 160). In a variant of this form, the final part of the movement of member 142 deenergizes the pulling coil, this final movement being assisted by the spring loading of a ball detent.