Where on the machine should the cable-pull servo motor be mounted?
The servo should be mounted on the chassis or on a solid body section so that it gives a straight cable route towards the throttle lever as far as possible. Keep it away from hot spots such as the turbo and exhaust manifold and from the areas with the highest vibration. The product data does not state an operating temperature range or an enclosure IP rating for the servo, so choose the mounting location conservatively.
Three criteria determine the mounting location.
- Cable route: set up a line between the servo and the throttle lever that is as straight as possible and free of sharp bends. Every sharp bend increases friction and hysteresis; the same potentiometer position starts to give a different speed.
- Temperature: electronics mounted in the engine bay are typically designed for a high ambient temperature, but turbo/exhaust surface temperatures go far above that. Do not mount the servo directly adjacent to the manifold or the turbo outlet; use a heat shield if necessary.
- Vibration: in automotive electronics, vibration tests are typically performed in the 10 Hz – 2000 Hz band. Attach it to rigid points such as the chassis/body, not to thin sheet metal panels; use a vibration-isolated carrier where possible.
Further practical notes: keep the cables away from hot and moving parts and fix them with cable ties, leave the cable going to the socket pointing downwards to form a drip loop, and place the servo somewhere accessible for maintenance and calibration. The cable guides and black cable ties in the GS740-3P kit are supplied for this tidy routing.
Full topic: Electronic speed and throttle control on diesel engines