GB854252A - Improved transmission mechanisms and controls therefor - Google Patents

Abstract

854,252. Variable speed and reverse gear; change-speed control. GENERAL MOTORS CORPORATION. Dec. 31, 1958 (Jan. 9, 1958], No. 42175/58. Class 80 (2). In a fluid-operated changespeed control in which the first ratio supply line from a manual selector valve is blocked in the neutral position, a one-way by-pass exhaust passage is provided to the selector valve, which passage is closed by fluid pressure except when the selector valve is in the neutral position. Gearing.-An hydraulic torque converter 10 having an hydraulically - operated lock-up clutch 31 drives an input shaft 48 by chain drive 47. Two-speed unit 12 driven from shaft 48 comprises run 49, planet 51 and ring 56 gears with hydraulic brake 58 and clutch 63 to provide two speeds to intermediate shaft 54. Three-speed unit 14 comprises two sun, planet and ring gear trains with hydraulic brakes 84, 74 and hydraulic clutch 86 to provide three speeds from shaft 54 to output shaft 71. The shaft 71 carries a sliding gear 91 to mesh with idler 96 or engage internal teeth on a gear 93 to provide reverse or forward drive from shaft 71 to drive shaft 104. A power take-off shaft 44 is driven from the converter casing through an hydraulic clutch 42. Fluid supply.-A pump 126 driven from the input side of the gearing delivers fluid to a pressure regulator valve 130 which maintains pressure in the main line 112 at either of two values selected by a manual valve 157. The higher pressure is obtained by fluid in chamber 142 holding a piston 141 to a stop 140 to bias the regulator spring 138. The converter fluid is supplied by passage 151. Control valve and accumulator.-The line 161 leads by secondary orifice 191 to a control valve 118 and accumulator 119 which regulate the pressure rise in line 210 leading to manual selector valve 300. In the restricted position shown which occurs with pressures in, excess of 20 p.s.i., the valve 193 is held againstthe spring 197 and fluid flows to the accumulator through primary orifice 198 and passage 199, at this pressure the accumulator commences to charge and is fully charged at 80 p.s.i. With pressures less than 20 p.s.i. the valve 193 is in the unrestricted position to the right and fluid flow is only restricted by orifice 191. The control valve and accumulator thus provide a fast fill of an engaging clutch or brake up to 20 p.s.i., then slow pressure rise for gentle engagement from 20 to 80 p.s.i. as the accumulator is charged through orifice 198 and finally, when the accumulator is charged, a faster pressure rise to holding pressure through orifice 198. Selector valve.-The manual selector valve 300 has a valve element 301, having lands a, b, c, d, e and f of equal diameter, which is resiliently held in the five ratio and neutral positions by detent ball 303 and grooves 304. The positioning of the lands and the supply lines 311, 312, 326, 329 and 326 to underdrive and direct drive of the two-speed unit and low, intermediate and high of the three-speed unit are such that the required pairs of drives are provided for each of the fine transmission ratios. The supply 326 is blocked by the land d in the neutral position, but exhaust from the low speed is obtained through a one-way by-pass valve 316 and connection 314. In conditions other than neutral this valve 316 is held closed by fluid pressure from connection 314 from the space between lands a and b, and connection 326 may provide for pressure or exhaust as required. Lock-up clutch valve.-Fluid from line 112, through restrictor 282, passes to a lock-up clutch manual valve 121 feeding the clutch 31 through line 261 or exhausting it through line 262. The clutch cooling line 275 is connected to cooling line 287 wheh the valve is in the engaged position. Power take-off valve.-A trimmer valve 271 is used to control the pressure rise in the lockup clutch 35 and the power take-off clutch 43 to provide gentle engagement. The clutch 43 is manually controlled by a valve 122 similar to the valve 121.