The motor runs but the cable does not pull the lever, what is the reason?

If the servo turns, the electrical side works and the fault is mechanical. Usual causes: the cable slipping in its socket, lever resistance and route friction.

If the servo motor is turning, the electrical and control side is working; the problem is mechanical. There are three usual causes: the cable slipping in the socket of the kit or having been attached loosely, the movement resistance of the lever exceeding the pulling force of the kit, and the friction produced at sharp bends along the cable route. Hunting for a fuse, a wire or a switch without telling these three apart first is a waste of time.

Make one distinction first

Does the cable not move at all, or does the cable move while the lever stays where it is? In the first case the problem is in the connection between the kit and the cable. In the second it is in the connection between the cable and the lever, or in the lever itself. That one question halves the search area and saves you from needless dismantling; answer it before you open the bonnet.

Check in this order

The order matters: each step makes it easier to eliminate the next, so do not skip any.

1. The cable connection: confirm that the outer end of the cable is fixed tightly in the cable entry socket of the kit and cannot slip. Slipping is the most frequent cause.
2. The cable length: if it is slacker than it should be, the whole pull distance (60 mm on the LFT20, 50 mm on the LFT54) is spent taking up the slack and no movement reaches the lever. Knowing what the pull distance describes speeds this step up.
3. Mechanical resistance: disconnect the kit and pull the lever by hand. If it moves stiffly even by hand, grease the joints and clean off the rust and mud. If the resistance exceeds the force limit of the kit, no adjustment will give a result.
4. The route: if the cable passes through sharp bends or a pinched guide, friction swallows a significant part of the force. Lay the route as straight as you can.
5. The condition of the cable: strands starting to break, a crushed sheath and water frozen inside all obstruct the movement.

Is it force that is short, or distance?

Telling the two apart is easy: pull the lever by hand and see where the movement stops. If the lever does not stir at all it is force; if it stirs but does not complete its full stroke, it is distance that is short.

If the force limit is being exceeded, lower the resistance first. If the lever still moves stiffly after the joints have been greased, the rust cleaned off and the route straightened, moving to the model with the higher pulling force may be necessary. If it is distance that is short, changing model is not always the answer; in most cases taking up the cable slack is enough, because the distance being lost is at the connection and not at the lever.

A cable does not come with the kit

On both models the existing cable of the tractor is used; no cable comes with the kit. That is a deliberate choice made so as not to remove a working cable for nothing, but it leaves the responsibility with you: the performance of the kit cannot be measured soundly with a worn cable. If the sheath is crushed or the inner liner torn, the friction grows day by day and the problem comes creeping back a while after it has been put right. In winter this effect becomes marked; water freezing inside the sheath can lock the movement completely.

When to change a part

If the trouble persists after freeing the cable and the joints, move on to the force comparison: judge whether the force needed to move the lever stays below the pulling force of the model you are using. That is the only thing that changes the result. Struggling with the fuse, the switch or the electrical settings is a waste of time at this point, because you can already see that the motor is turning. The order of decision is clear: connection first, then mechanical resistance, then the route, and the model last.

The full topic: Converting a tractor hydraulic lever to electronic control

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