Patent GB-808318-A (GB)
Title: Improvements in or relating to variable ratio power transmission apparatus
Inventor: HOBBS HOWARD FREDERICK
IPC: F16H59/20
Filed: 1955-12-13
Abstract: 808,318. Change-speed control. HOBBS TRANSMISSION Ltd. March 12, 1957 [Dec. 13, 1955], No. 35731/55. Class 80 (2). A kick-down or similar shift mechanism associated with the throttle of an engine driving a change-speed gear in a motor car, is provided with means which permits the throttle to be partially closed after a kick-down shift without causing an upshift. The ratio in the change-speed gear is selected automatically in accordance with the output speed of the gear and, except for the kickdown shift, independently of the throttle setting. In one form, a lever 11, Figs. 1, 2 (Provisional), is fast upon a shaft 10 carrying an arm 12, Fig. 3 (Provisional). A strut 14 connects the arm 12 to a beam 13. At one end of the beam 13, a rod 16 leads to a pressure engaging relief valve in an hydraulic circuit of engaging ratio establishing clutches. At the other end of the beam 13, a rod 17 is connected to a kick-down valve in the hydraulic circuit, actuation of this valve causing a downshift in the changespeed gear. On depressing the vehicle accelerator pedal, first the rod 16 is moved upwardly as far as it will go to increase the pressure of the liquid engaging the clutches. In this position, the throttle of the motor car engine is fully opened. On further depression of the accelerator pedal, the shaft 10 continues to turn and, due to the increased leverage, raises the rod 17 to open the kick-down shift valve and effect the required downward ratio shift. A latch 19 pivots about a pin 20 and is biased by a spring 21 to engage the end of an adjustably positioned screw 22. When the accelerator pedal is depressed to its kickdown position, a projection 23 on the latch engages beneath an extension 18 of the beam 13. When the accelerator pedal is released from its kick-down position, the projection 23 holds the beam 13 in its upward position, with the kickdown valve open, until the throttle has been partially closed. Complete release of the accelerator pedal removes the projection 23 from the extension 18 of the beam 13, and allows the kick-down valve to close. Adjustment of the accelerator position at which the kick-down valve is closed is effected by means of the screw 22. In a modification, an accelerator pedal 45, the Figure (Complete), is connected through a spring lost motion link 62 to a throttle 64, and through links 44, 42 to a shaft 40. An arm 47 on the shaft 40 operates a rod 16 which, as before, controls the setting of the pressure relief valve in an hydraulic circuit engaging ratio establishing clutches in the change-speed gear. The shaft 40 also carries an arm 50 on which is mounted a link 52 having an end spigot 53, engaging with lost motion in a slot 56 in a rod 17 controlling the kick-down valve. Having depressed the accelerator pedal 45 to its kickdown position, the kick-down rod 17 is pushed upward by the link 52. Hydraulic pressure acting upon the kick-down valve retains the valve in this position on release of the accelerator pedal, until the lost motion between the spigot 53 and the slot 56 has been taken up, thus allowing partial closing of the throttle before upshift occurs. The amount of lost motion in the slot 56, and hence the position of the accelerator pedal 45 reached before upshift occurs, is adjusted by means of a screw 55. Specification 738,588 is referred to.