Setting Belt Tension; Tools Required; Motor Drive Box - Raymarine ST4000+ Service Manual

3.3 Setting Belt Tension

18 ST4000+ Autopilots Service Manual 83115-1
The purpose of the belt tensioning procedure is to ensure that:
1. The belt is sufficiently tight to transmit the normal maximum drive
torques.
2. The belt is not over-tightened, as this will increase the backdrive load to a
level where it can be felt on the vessel's wheel.

Tools required:

4000 Drive unit torque fixture
Service tool number - T033
4000 Drive unit torque adjuster
Service tool number - T032
Motor drive box and ammeter

Motor drive box

FS1
15A
12V
BATTERY
D1
+
MR752
Figure 9. Motor drive box circuit diagram
IC1
LM396K
C1 C2 R2
+ +
4700uF 4.7uF 845R
ST4000+ Autopilots
SW1
R1
121R
Red (ZO78)
Brown (Z077)
ACTUATOR
Blue
C3 C4 R3
+
22uF 4.7uF 1KO
D2384-1