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).
Provisional specification detailing improvements to change-speed gearing mechanisms.
Identifier | ExFiles\Box 136\4\ scan0161 | |
Date | 20th October 1932 | |
2 402,924 but to so engage its slot at one time the remaining link bars resting on the peri- phery of the shaft. A neutral position is provided in which no link can engage 5 its slot. The disengaging camshaft is suitably coupled to the engine clutch pedal and the selector shaft is suitably connected to a hand controlled lever. The selector 10 shaft is preferably turned through the medium of a toothed rack or quadrant that meshes with a pinion on the selector shaft. Flanges may separate the slots in the selector shaft. 15 Assuming the top speed of a four-speed gear to be engaged and it is desired to change down to third speed the lever con- trolling the selector shaft is moved to bring the third speed slot in the shaft to 20 its top position. The corresponding link bar will slightly engage the slot and the end of the bar will rest on the arm or wing of the shift lever that has to func- tion to make the gear change. This 25 operation may be made at any time in advance of the actual gear change. To effect the gear change the engine clutch pedal is depressed and this causes the disengaging camshaft to give an axial 30 movement to the peg and shift fork of the top speed and so disengage that gear. The same movement of the camshaft slides the link bars outwards and as the third speed link bar is engaged with its slot in 35 the selector shaft and can drop still fur- ther into the slot it falls over the end of the shift lever arm or wing at the end of its outward movement the peg or equiva- lent on the end of the link bar then engag- 40 ing the arm or wing. By releasing the engine clutch pedal the camshaft returns to its normal position and in doing so gives an inward movement to the link bar causing the latter to give a pull on 45 the shift lever that slides the shift fork axially to engage the third speed member. The camshaft may be returned to its normal position by means of a separate spring or its return may be effected by 50 means of the clutch pedal spring or clutch spring or any combination of these. Clearances and neutral channels may be provided on the camshaft where desirable. Locating plungers or pawls may also be provided to locate the various parts of 55 such of these as desired. My invention may be varied in its arrangement by pivoting the link bars on the shift lever and adapting their free ends to engage studs or equivalent on the 60 camshaft or alternatively by providing a peg on each link bar that can be moved by a cam face on the link bar or on a ring attached thereto. When desirable the camshaft may engage with a peg on 65 the shift lever instead of on the shift fork. If desired the camshaft itself may be coupled by suitable cranks or the like to the loose member of the engine or equiva- 70 lent friction clutch as such an arrange- ment may be advantageous in the case of small gears such as are used on motor cycles and similar light vehicles. Preferably the gear change is effected 75 before the engine clutch re-engages and a dash-pot or equivalent may be provided to retard the re-engagement of the clutch members. My invention may be applied to motor- 80 cycle gearboxes in substantially the same manner as described and adapted to either hand control or foot control of the engine or equivalent friction clutch. My invention can be employed with 85 change-speed gears using the synchro- mesh form of gear changing in which friction cones or the like are employed as means of synchronising the speeds of the members to be engaged prior to their posi- 90 tive engagement and also with change- speed gears employing a free-wheel or other coupling between the gear shaft and the propeller shaft. My invention can also be employed with 95 any form of hydraulic or automatic clutch or coupling. Although for convenience of description my invention is herein described as being arranged above the gear members it is 100 within the scope of my invention to arrange it in any other position in the gearbox that is suitable for its operation as described. Dated the 20th day of October, 1932. A.{Mr Adams} ALLTREE. PROVISIONAL SPECIFICATION. No. 30,969, A.D. 1932. Improvements in and relating to Change-speed Gearing. 105 I, ARTHUR ALLTREE, Rydal Dene, in the County of Lancaster, British sub- Pilling Lane, Preesall, near Fleetwood, ject, do hereby declare the nature of this 402,924 3 invention to be as follows :— My invention relates to improvements in pre-selector gear change mechanism for use with change-speed gearing of the type 5 in which certain elements or members of the gear are positively engaged with other elements or members or moved into mesh therewith to effect a gear change, said mechanism being applicable to any 10 form or arrangement of this class of gear- ing as used on motor cars motor cycles or other motor vehicles. According to my invention a bar is arranged parallel with the gear shaft 15 and upon this bar shift forks that are adapted to slide those members of the gear that are moved to effect gear changes are suitably mounted. A peg is provided on each shift fork and this peg is adapted 20 to be engaged by the forked end of a shift lever which has its other end pivoted to a convenient part of the gearbox casing. A camshaft is mounted parallel with 25 the shift forks bar and this camshaft is formed with cam faces that when the camshaft is partially rotated will dis- engage any gear that may be engaged moving the shift fork corresponding with 30 such gear into its neutral position the cam face acting on the peg. The cam- shaft is provided with a cam for each gear change and reverse and its primary object is to ensure that no gear is engaged at 35 the moment a gear change is being made. As an alternative to the use of a single peg on the shift fork I may provide two such pegs one for the shift lever and the other for the camshaft. 40 In a further alternative I may provide a second shift lever adapted to engage with the single peg on the shift fork or with the second peg. This second shift lever is provided with a peg that engages 45 with and can be moved by the camshaft to cause the second shift lever to slide the shift fork into its neutral position. The second shift lever is mounted in sub- stantially the same manner as the first 50 shift lever but preferably on the opposite side of the gearbox. In any arrangement the camshaft may be formed with recesses to receive the pegs when the camshaft is in its normal or 55 inoperative position one recess to receive the peg in its neutral position and an- other recess to receive the peg in its en- gaged position the object being to keep the shift forks and gear members corre- 60 sponding therewith in their neutral or engaged positions as the case may be. When one shift fork has to move axially in two directions to effect two gear changes a single neutral recess is provided 65 with a recess on each side of it corre-sponding with the engaged position of each gear change. Rollers may be mounted upon any of the pegs to facilitate operation or reduce wear. 70 Link arms or bars are pivoted to the camshaft one link bar for each forward speed and one for reverse and these link bars are adapted to be engaged with suit- able arms or wings provided on the shift 75 levers. Guides may be provided to take any side stresses on the link bars and a slotted plate or plates secured to the gear- box casing may serve for this purpose the link bars sliding in the slots. 80 A selector shaft arranged parallel with the camshaft is employed to determine which link bar shall be engaged the selector shaft being formed with slots equal to the number of link bars and deep enough to permit the link bars to engage 85 with the shift levers the slots being so spaced around the shaft that when the latter is rotated each slot in turn comes into a position in which its link bar can engage with the corresponding shift lever. 90 A neutral position is provided in which no link bar can engage with a shift lever. The disengaging camshaft is suitably 95 coupled to the engine or equivalent clutch pedal and the selector shaft is suitably connected to a hand controlled lever the selector shaft preferably being turned through the medium of a toothed rack or quadrant that meshes with a pinion on 100 the selector shaft. When desirable the camshaft may be operated by means of a hand lever or pedal other than the clutch pedal. A spring or springs may be employed 105 to return the camshaft to its normal posi- tion after use one end of the spring being secured to the camshaft or to an arm or lever thereon and the other end anchored to the gearbox casing. 110 As an alternative to engaging with a peg or pegs on the shift forks the first or second shift levers may be adapted to engage slots formed in the shift forks either separate slots or a slot common 115 to each pair of levers. If desired the selector shaft may be arranged at or near the free ends of the link bars and in such an arrangement a middle part of each link bar may be adapted to engage with its shift lever. 120 Alternatively each link bar may be pivoted at about its middle to the cam- shaft thus providing two free ends one of which is controlled by the selector shaft 125 and the other adapted to engage with the shift lever. In use partial rotation of the camshaft ensures that no gear is engaged and the same movement engages a link bar with 130 | ||