John Deere ET-3103-J 用户手册

20 

 

 

 Cordless Impact Wrench Operator's Manual 

  

7.  Confirm the tightening torque:

 

The following factors contribute to a reduction of the tightening torque. So confirm  

 

the actual tightening torque needed by screwing up some bolts before the job with  

 

a hand torque wrench. Factors affecting the tightening torque are as follows.

 

a.  Voltage:

 

 

When the discharge margin is reached, voltage decreases and tightening  

 

 

torque is lowered.

 

b.  Operating time:

 

 

The tightening torque increases when the operating time increases. But the  

 

 

tightening torque does not increase above a certain value even if the tool is  

 

 

driven for a long time. (See Fig. 16)

 

c.  Diameter of bolt:

 

 

The tightening torque differs with the diameter of the bolt as shown in 

 

 

Fig. 16. Generally a larger diameter bolt requires larger tightening torque.

 

d.  Tightening conditions:

 

 

The tightening torque differs according to the torque ratio; class, and length  

 

 

of bolts even when bolts with the same size threads are used. The tightening  

 

 

torque also differs according to the condition of the surface of workplace  

 

 

through which the bolts are to be tightened. When the bolt and nut turn  

 

 

together, torque is greatly reduced.

 

e.  Using optional parts:

 

 

The tightening torque is reduced a little when an extension bar, universal  

 

 

joint or  long sockets are used.

 

f. 

Clearance of the socket:

 

 

A worn or deformed hex or a square-holed socket will not give an adequate  

 

 

tightness to the fitting between the nut or anvil, consequently resulting in loss  

 

 

of tightening torque. Using an improper socket which does not match to the  

 

 

bolt will result in an insufficient tightening torque. 

 

g.  Tightening torque varies, depending on the battery’s charge level Fig. 18  

 

 

shows an example of the relationship between tightening torque and the  

 

 

number of tightenings. As shown, tightening torque gradually weakens with  

 

 

the increase in the number of tightenings. In particular, as the torque    

 

 

decreases very close to the complete discharge (“a” margin in graph), the  

 

 

unit’s impact weakens, the number of time impacts declines and tightening  

 

 

torque drops off abruptly. If this occurs, check torque level, then recharge the  

 

 

battery if necessary.