From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Patent specification for improvements in change-speed gearing, specifically for preselector semi-automatic control for synchromesh gears.
| Identifier | ExFiles\Box 136\4\ scan0160 | |
| Date | 21th October 1932 | |
| PATENT SPECIFICATION Application Date: Oct. 21, 1932. No. 29,433/32. 402,924 This specification relates to methods of preselector semi-automatic control for synchromesh gears. PROVISIONAL SPECIFICATION. No. 29,433, A.D. 1932. Improvements in and relating to Change-speed Gearing. I, ARTHUR ALLTREE, Rydal Dene, Pilling Lane, Preesall, near Fleetwood, in the County of Lancaster, British subject, do hereby declare the nature of this invention to be as follows :— My invention relates to a new or improved form of pre-selector gear change for use with change-speed gearing of the type in which the gear changes are effected by sliding toothed gear members into mesh or by means of sliding dog or equivalent clutches provided on the gear shaft or shafts of the gear or by providing dogs or teeth on adjacent gear members so that they may be positively coupled together to make the loose member operative to effect a gear change or by a gear member formed with dogs or teeth that can be engaged with corresponding dogs or teeth formed on or secured to the gear shaft upon which it is mounted my invention being primarily intended for use with gearboxes of the type commonly used on motor vehicles. My invention comprises a bar arranged parallel with the gear shafts the said bar being fixed to the gearbox casing and adapted to carry the shift forks by means of which the gear members are shifted to make the gear changes. The shift forks are mounted loosely on the bar and their forked ends are engaged in the usual manner with the gear members. Assuming the bar to be arranged over the top of the gear members the upper end of each shift fork takes the form of a vertical peg and this peg is engaged by the forked end of a shift lever. The shift lever is preferably arranged horizontally at right angles to the bar and the end furthest from the shift fork is pivoted to a suitable part of the gearbox casing. In the case of a shift fork that has to move axially in two directions from its neutral position the shift lever is formed with an arm or wing on each side the arm or wing projecting from the main body of the lever. When the shift fork has to move in one direction from its neutral position as in reverse gear a single arm or wing is provided. Above the shift forks and shift fork bar a camshaft is mounted parallel with the bar and this camshaft is formed with cam channels into which the pegs on the shift forks extend and the cam channels are so formed that when the camshaft is partially rotated the cam faces move the pegs into neutral position the object being to ensure that any gear that may be engaged is freed from such engagement and the shift fork moved into its neutral position when the camshaft is rotated to the desired extent. This camshaft is adapted to function prior to the engagement of any gear when gear changing as hereinafter described. The upper portion of the disengaging camshaft is formed with deep slots to house the pivoted ends of link bars one link bar being provided for each speed provided by the gearbox including reverse when this has a separate movement. The free end of each link bar is provided with a peg or equivalent that projects downwards from the bar. Each link bar may pivot on a separate stud but preferably a long stud or spindle extending right through the length of the camshaft may serve as a pivot for all the link bars. Parallel with the disengaging camshaft and under the link bars is mounted a selector shaft formed with slots the latter being cut across the shaft in the same direction or plane as the link bars and there is one slot to each link bar. Normally the link bars rest upon this shaft and are kept in contact with it by means of springs that give a downward load on the link bars. The arrangement is such that when the shaft is rotated each slot in turn comes to a top position and when in this position the link bar corresponding with the top slot can fall into the slot under the force or pressure of its spring. The slots are suitably spaced around the shaft to permit only one link [Price 1/-] | ||