TM 9-2520-246-34 Section V. DESCRIPTION, OPERATION, AND DATA (MODEL T-136-21) 4-18. General. This section provides repair instructions for the sprag equipped transfer, model T- 136-21 4-19. (See fig. 4-26 and 4-27.) Description and Operation. a. Description. Sprag equipped transfer, model T- 136-21, is a 2-speed synchromesh unit driven from the transmission by a propeller shaft. The transfer distributes power to front and rear axles through the propeller shafts. In addition to high and low speeds, the transfer gearing is designed to drive the front axle slightly slower than the rear axles and this difference in speed is taken up by an overrunning sprag unit on the front output shaft during normal operation. When the rear wheels lose traction, the sprag unit automatically engages, causing the front wheels to drive the vehicle also. The handbrake drum is mounted on the transfer-rear-output-shaft companion flange. (See fig. 4-27.) which moves the synchronizer into contact with the input shaft low-speed gear or the input shaft high- speed gear. Power is distributed to all three axles, although the overrunning sprag units allow the front wheels to turn freely until the rear wheels lose traction, at which time the front wheels are engaged drive also. (1) Low Range. When the transfer is shifted to low range, the synchronizer assembly is moved forward on the input shaft to engage the input shaft low-speed gear which is in mesh with the idler shaft low-speed gear. Because the low-speed gear is keyed the idler shaft, the power flow is through the idler shaft gears, to the rear and front output shaft and shaft gears, and to the companion flanges. (2) High Range. When the transfer is shifted into high range, the synchronizer assembly is moved rearward on the input shaft to engage the input shaft high-speed gear which is in mesh with the idler shaft high-speed gear. Because the high-speed gear is keyed to the idler shaft, power flow is through the idler shaft gears to the rear and front output shaft and gears. b. Operation. The selection of high or low range in the transfer is accomplished by a shifting mechanism, in to Figure 4-26. Sprag Quipped Transfer Model T-136-21 — Front View. 4-19