Yanmar 4LHA-HTP Operation Manual page 666

Chapter 9 Electrical System
7. Tachometer
7. Tachometer
7-1 Construction of tachometer
The tachometer indicates the number of revolutions per
minute by means of an electrical input signal which is
generated as a pulse signal from the magnetic pickup sen-
der (MPU sender).
The function of the sender is to convert the rotary motion
into an electrical signal by means of counting the number
of teeth of the ring gear connecting with the flywheel
housing.
Rotation
detecting sender
7-2 Specifications and dimensions of tachometer
(1) Specifications
Rated voltage
Range of operating voltage
Illumination
No. of teeth
Ring gear Ring gear
Module
Part No. of tachometer
Part No. of sender unit
Tachometer sensor
Red/black
Orange
Blue/red
Black
Tachometer
DC 12V
10 <* 15V
3.4W/12V
127
254
120130-91200
(128696-91100)
128170-91160
(2) Sensitivity limit of sender unit
Ring gear speed
(m/sec)
10
0.5 1.0
Sender unit and ring gear clearance C (mm)
Ring gear
(3) Dimensions of sender unit
25 ±0.5
(0.9646 ~ 1.0039)
1.5 (0.0591)- -3(0.1181)-
M18x P1.5
(4) Dimensions and shape of tachometer
Identification mark
9-40
4LHA Series
G zone
/
NG zone
1.5 2.0 2.5
Sender unit
34.5(1.3583)
5(0.1969) 4.5(0.1772)
15.5
(0.6102)
72.3 (2.8465)
10 (0.3987)-
mm (in.)