Rod and Fork Gear Selectors
The driver can select and engage individual gear ratios by a gear selector mechanism. There are three selector rods at their end, protected either in the actual housing of the selector box or within the housing for the selector cover. The selector forks rib over or on these rolls and fit on the outer sliding-dog clutch hub over saddle-like grooves When a lever fork is moved to one of the constant-mesh gearwheels, the specific dog-clutch hub passes over the exposed ring of the dog's teeth. The lay-shaped cluster gear will be attached to the main output shaft once the teeth of the hub and gear-wheel have meshed so as to complete the power-flow track across the gearbox. The selector gaps have to be moved directly over the internal hubs for the neutral equipment. It triggers a separate revolution of each gearwheel on the main shaft (Fig. 25.14).
Gear-change Lever Action
The transmission lever is a forge stainless steel rod with an upper end frozen on it with a control button and a bottom end flat on both sides. The focal point for the heel selection operation is given by a pivot ball, positioned at about one-fifth of the length of the lever from the bottom end (Fig. 25.14). In the selector rod window, the bottom spherical end matches so that the worked flats are parallel to the rods. In a socket machined in the lever cast, is the swivel-ball portion of the lever. The lever pivot is fitted with a spring-laden dust cover and a spherical washing machine carrying a lever ball in place (Fig. 25.15).
The lever is inclined to the right corners of the rods in order to select and enforce a gear ratio. This causes the spherical lever end to pass through the three pick-up doors so that the rods match the desired gearwheel. The lever button is then moved into a position alongside the selector rods that move through the dog's outer hub through the selector buckle over the dog's teeth on the side of the chosen gearwheel.
Spring-loaded Ball or Plunger and Selector-rod Grooves
Spring-loaded balls and dippers and grooves (notches) are used to position and hold selected rods. The spring load forces the balls to align themselves (Fig. 25.15). There are three grooves for each of the two forward selector rods, and two grooves for each reversed selector. When the selector rods and their forks move one way or two, they finally align themselves with the balls or plungers loaded at spring when they reach a gear position. The middle rail on the forward gears is neutral and the railings on either side are engaged in the first, second, third, or fourth gears. The rail is neutral in place. There is only a neutral and opposite position in the reverse selector.
Fig. 25.14. Rod-and-fork gear-selector arrangement
Fig. 25.15. Three-rod gear-selector mechanism with plunger-and-pin interlocking device
