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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).
Detailed description of a change speed transmission mechanism.

Identifier  ExFiles\Box 136\4\  scan0149
Date  14th February 1933 guessed
  
4 1,897,851

shift rod 151. There may be three notches, a middle one for the neutral position of the rod, and end notches for third speed and second speed positions.
5 The shift lever 157 enters an enlarged space 159 having end walls 161. Within the space 159 the lever snugly engages a lock bar 163 which is slidable within the shift rod 151. The lever is operable to shift the
10 lock bar prior to its engagement with the end walls 161 to shift the rod. A spring 165 is secured to the rod. Its arms engage the end of the lever 157 and hold the lever in its mid position in the space 159. The
15 lock bar has two angularly walled notches 167 located adjacent each other. Between the notches there is a flat face 169 upon which the plunger may rest. When resting on this flat face 169 it is projected into one
20 of the notches 153 of the casing. In a neutral position the shift rod is therefore locked by the plunger to the casing. If the lever is actuated it first moves the lock bar, due to the clearance between the end of the lever
25 and walls 161 within the space 159, and the plunger 155 drops into one of the notches 167. In this way the rod 151 is disconnected from the casing. Thereafter the lever 157 engages one of the end walls 161 and both
30 shift member 151 and the lock bar move together. The shift member 151 reaches its speed ratio position when the plunger 155 is opposite one of the end openings 153. Upon the release of the lever 157 the spring
35 165 restores the lever to its mid position in the space 159 and thereby moves the lock bar just sufficiently to push the plunger 155 from the notches of the lock bar and into engagement with the casing. In this way
40 the shift rod 151 is locked not only in neutral but in both its gear ratio positions and from the several positions it may be moved only after the relative motion between the lock bar and the shift rod has been taken up.
45 In Figs. 16-20 inclusive is another form which the invention may take. In this form of the invention 301 represents the housing of the change speed transmission and 303 the cover. Through the cover projects shift
50 lever 305.
Secured to the cover by fastening means 307 is a supporting plate 309 which is apertured as shown in Fig. 20. Mounted to slide longitudinally of the housing and on
55 this plate 309 is a cam plate 311. This cam plate has three countersunk holes 313, 313' and 313'' adjacent one edge. It has two openings 315 located as shown for the passage of the fork arms 317. It has a central
60 opening 319 dimensioned to permit the lever end to move transversely for engaging either of the forks but also so dimensioned as to move longitudinally with all longitudinal movements of the lever.
65 Numerals 321 and 323 represent the two forks. One of them, fork 323, this being the fork for the high and second speed shifts, has three openings 325, 327, 329. Of these three openings 327 is chamfered and the end
70 openings 325 and 329 are countersunk. Secured to the cover and located above the forks is the plate 331. This plate has a slotted formation as shown at 333 for the passage of the shift lever, and is provided
75 with dividing plates 335. It has an opening 337 successively overlying openings 325, 327, and 329 as fork 323 moves longitudinally. It also has another opening 339 similar-ly related to recesses 341 of fork 321, the
80 low speed fork. Also shown in the drawings, there is a spring-pressed plunger in the cover operable through opening 339 to engage in the recesses 341, this construction to serve as a detent to yieldingly hold the
85 low speed fork in its several positions of longitudinal adjustment. No novelty is alleged for this detent device associated with the low speed fork.
The cover 303 has an opening 341' for the
90 reciprocation of a plunger 343 actuated by a spring 345. This plunger extends through the opening 337 and its lower end is formed with a cylindrical part 347 and a tapered part 349. Balls represented by numerals 351,
95 351', and 351'' are used in the openings 325, 327, 329 and the cam plate openings there-beneath.
The notch 353 of the fork 323 is so dimensioned that the lever 305 moves the cam
100 plate to a limited extent before it engages this fork.
The end holes 313 and 313'' are spaced from the intermediate hole 313' to a somewhat greater extent than are the end open-
105 ings 325 and 329 from the middle opening 327 in the fork 323. This arrangement is well illustrated in Fig. 17.
To understand the operation of the device reference is made to Figs. 16-18. Fig.
110 17 shows the parts in a neutral position. The middle opening 313' of the cam plate and the chamfered opening 327 of the high speed fork are in registration with the plunger 343. The ball 351' is partly in the
115 cam plate and partly in the fork. The balls 351 and 351'' only slightly project into the notches of the cam plate, owing to the great-er distance of the end notches of the cam plate from the intermediate notch. The
120 tapered end of the plunger engages the chamfered slot 327. As the lower end of the lever moves to the right the cam plate is moved before the lever picks up the fork. This first movement of the cam plate rela-
125 tive to the fork raises the ball 351' from the cam plate into the fork opening, the plunger being thereby lifted from engagement with the fork. This movement also brings hole 313 into registration with 325.
130 The lever thereafter moves the fork and
  
  


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