TM 9-2520-246-34-1 (2) Positive locking transfer, model T-136-27, shown in figure 1-3 is a two- speed synchromesh unit driven by the transmission propeller shaft. This transfer has an air selector valve that lets the air locking assembly engage the front output shaft to the rear output shaft for driving the front axle. Selection of the high or low ranges of the transfer gives the truck operator a total of ten forward speeds and two reverse speeds. (3) Transmission transfer model T-136-21, figure 1-4 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 and the front wheels also drive the truck. d. Power Takeoffs (Models WN-7-28, WND-7-28, and P-136-C). (1) Power takeoff models WN-7-28 and WND-7-28, (figure 1-5 and 1-6) are driven by the transmission and give power to drive the truck winches, pumps, and other special or auxiliary equipment. Both power takeoffs are made to be mounted on a Society of Automotive Engineers’ (SAE) standard, six-bolt hole power takeoff open– ing. However, when needed, these units may be mounted on four-hole openings if suitable filler blocks and driving gears are used. Both units are of the heavy-duty type, having two forward speeds and one reverse speed. The units can be used for either left or right hand mounting on the drive mechanism. The shifter shaft goes through both ends of the case so that the shift linkage can be hooked up to either end of the shaft. (2) Power takeoffs WN-7-28 and WND-7-28 are the same except that power takeoff model WND-7-28 uses two output shafts, and model WN-7-28 has only one out- put shaft. (3) Power takeoff model P-136-C (fig. 1-7) is a single drive, one-speed unit which is made to mount on transmission transfers only. The outer carriers are circu- lar in shape and support the main drive shaft and driveshaft bearings. This unit is used to drive many different types of auxiliary truck equipment. 1-6