Lift Arm
These are the two short arms sitting on top of the tractor body that transfer the movement of the hydraulic lift cylinder to the lower links. The cylinder rotates them on a shaft; that rotation is converted through the lift rod into vertical movement of the lower links. Lift capacity depends largely on the length ratio of this arm.
The lift arm acts as a lever: the short-stroke but high-force movement produced by the cylinder is turned, in proportion to the arm length, into a longer but lower-force hitch movement. That is why different tractors show different lift capacities at the same hydraulic pressure.
- If the key or clamp connection of the arm on the shaft loosens, the hitch responds late to commands.
- The choice of the lift rod attachment hole (where alternative holes exist) changes the force-stroke balance.
- With insufficient lubrication the shaft bushings wear and the arms drop slightly under load.
Electronic retrofit kits do not touch the lift arm at all. The LFT20 and LFT54 pull the control cable; the arm movement still comes from the tractor's own hydraulics. So if the hitch rises slowly, pump flow, oil level and mechanical play are checked first; the kit's pull force (10 kg on the LFT20, 15 kg on the LFT54) is only enough to move the control lever, not to lift the load.
The context in which this term is used: What is Lift-O-Matic and how does it work?