CHAPTER 5. REPAIR OF POWER TAKEOFFS

TM 9-2520-246-34

CHAPTER 5

REPAIR OF POWER TAKEOFFS

Section I. DESCRIPTION, OPERATIONAL AND DATA (MODEL WN-7-28)

5-1. General. This chapter contains the rebuild

forward and backward on the shaft by the shifter fork

instructions for power takeoff models WN-7-28,

(Z). The other is the output shaft high speed gear (BB)

WND-7-28, and P-136-C.

which is free on the output shaft (H) and is in

constant mesh with the input gear (P). The sliding

5-2. Description (Figure 5-1). Heavy-duty power

gear (AA) is splined to the output shaft (H) and may

takeoff model WN-7-28, is designed for mounting on

be meshed with the spur teeth of the reverse gear

an SAE standard 6-hole or 6-stud power takeoff

(FF), with the spur teeth of the input gear (P) (for low

opening. The unit is designed to be mounted on the

speed operation) or may act as a clutch gear to couple

left or right side of the driving mechanism. The shifter

the output shaft high speed gear (BB) to the output

shaft extends through each end of the case so that the

shaft (H).

shifting control linkage may be attached at either end.

The output shaft extends from the front of the case

c. Shifter Fork. The shifter fork (Z) is attached to

the shifter shaft (A) by a capscrew. The fork engages

and is provided with a woodruff key for mounting the

winch propeller shaft companion flange. Boots are

the circumferential groove on the sliding gear (AA).

installed over the ends of the shifter shaft to protect

the surface of the shaft. The input gear of the power

takeoff is a cluster composed of a helical gear which is

constantly in mesh with the helical gear of the

transmission reverse idler gear, and the driving gear

which is of spur tooth construction. The power

takeoff has two speeds forward, neutral, and one

speed in reverse. A shifting mechanism provides for

selection of the desired speed and direction of rotation

of the output shaft. The shifting mechanism in neutral

position disengages the output shaft gears from the

driving gear.

5-3. Operation.

NOTE

Figure 5-1. Power Takeoff Model WN-7-28.

The reference letters in parentheses pertain

to figure 5-2.

5-4. Data.

a. Input Gear. The helical input gear (P) is in

National stock number . . . . . . . . . . 252040-7061137

constant mesh with the helical gear of the

Ordnance number . . . . . . . . . . . . . . . . . . . . . . . 7061137

transmission reverse-idler gear and therefore, is in

Manufacturer . . . . . . . . . . . Spicer Div. - Dana Corp.

constant rotation when the transmission is engaged.

Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WN-7-28

(Refer to transmission, Chapter 3.) The input gear (P)

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heavy-duty

is installed on a nonrotating input gearshaft (L) and is

Speeds . . . . . . . . . . . . . . . . . . . . . . 2 forward, 1 reverse

mounted on the input gear roller bearings (N). The

Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmission

shaft is pressed into the housing and secured with a

Input gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Helical

cotter pin. A thrust washer (M) is located at each end

Output shaft . . . . . . . . . . . . . . . . . 1 in. dia;5/16 in.

of the input gear. The helical tooth portion of the

keyway

input gear (P) is in constant mesh with the reverse

Bearings:

gear (FF) which is installed on the reverse gearshaft

Output shaft . . . . . . . . . . . . . . . . . . . Two-ball type

(JJ) and secured with the reverse gear pin (EE). The

Input shaft . . . . . . . . . . . . . . . . . . . . Two-roller type

reverse gearshaft rotates in two supporting bearings

Reverse gear . . . . . . . . . . . . . . . . . . Two-roller type

(GG and FF).

Horsepower delivered:

100 rpm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7

b. Output Shaft. The output shaft (H) is supported

500 rpm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

in the housing on two ball bearings (F and S). Two

1000 rpm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

gears are installed on the output shaft (H). One is the

Gear pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7/9 in.

output shaft sliding gear (AA) which is moved

Backlash (allowable) . . . . . . . . . . . . . . . . . . . . 0.008 in.

5-1