Abstract: A tripod type constant velocity joint is disclosed. A tripod housing defines an opening, and is formed with three track grooves which are communicated with the opening and are uniformly spaced apart from one another in a circumferential direction. Each track groove has a contact groove formed in a side wall section thereof, and the contact groove has a bottom wall part which defines a guide surface. A spider is disposed in the opening of the tripod housing. The spider has three trunnions which project from an outer surface thereof to be inserted into the three track grooves, respectively. Three pairs of a needle roller, a spherical roller and a cylindrical roller are sequentially and diametrically fitted around the three trunnions of the spider, respectively.

Abstract: A booster for a transmission gear box has an actuating rod cooperating with a gearshift lever and a hollow piston rod movably penetrating the pneumatic cylinder and cooperating with the actuating rod. A connector is mounted to the piston rod and introduces and discharges pressurized air into and from the piston rod. A striker is coupled to the actuating and piston rods through a pin and is coupled to a connecting lever of the gear box to allow the connecting lever to be operated in conjunction with the actuating and piston rods. The booster prevents a relative rotating motion between the actuating and piston rods, simplifies the gearshift part of the gear box, smoothly engages and disengages gears to the gear box with a small force and provides an easily-machinable hollow piston rod.