Rapier loom lubrication: why the cam box is not a gearbox
Most weaving halls run on one oil. That is rarely a technical decision — it is a purchasing decision, because one drum is easier to buy, store and issue than three. The loom has no opinion about how it was purchased. It just fails where the compromise is largest, and on a rapier loom that is the cam box.
The case for one oil is a good one, and it is wrong here
Standardising a plant on a single grade is not stupidity. It cuts stock, it removes the chance of the wrong drum being opened at three in the morning, and it gives you one supplier conversation instead of three. In a hall full of reduction gearboxes it is the right call.
A rapier loom is not a hall full of reduction gearboxes. Of the five lubrication points on a SOMET Super Excel — cam box, take-up worm gear, warp let-off worm gear, slow-speed box, weft selector — exactly one is the conventional gearbox duty that the standardisation argument assumes. The other four are not.
The cam box is where the bill arrives
The cam box converts continuous rotation into the reciprocating motion of the rapier drive. Every pick reverses the load direction. At 600 picks a minute that is twenty thousand load reversals an hour, in a box that runs warm and, in most mills, is not opened during the season.
An ISO VG 320 industrial gear oil is built for a steady rolling contact. It is a perfectly good oil. It is simply being asked to hold a film through a load reversal twenty thousand times an hour, which is not what it was formulated to do. The oil does not fail dramatically. The box gets noisy, then it gets hot, then someone schedules it for the next shutdown, and by then the surfaces are gone.
This is the point worth being stubborn about. If you concede every other lubrication point on the machine for the sake of a simpler purchase order, concede this one last.
Two worm drives, and they are not gearboxes either
Take-up and warp let-off both run worm gearing. Worm teeth slide rather than roll, so the load sits on the oil film instead of on the tooth geometry, and the heat has to go somewhere. Pick a grade on viscosity number alone and the film is the thing that gives way.
The same mechanism decides grade selection on coal-mill worm gearing in power generation, where the failure mode is pitting and spalling of the worm. The loads on a loom are a fraction of that. The mechanism is identical.
The spindles want the opposite of everything above
On the twister and the bobbin winder, spindle bearings run fast under almost no load. Here a heavy grade is not merely unnecessary — it is a cost. It raises drag, raises running temperature, and it does so on every spindle in the hall, every hour the hall is running.
MOTTA SH VG 10 is the grade carried for this duty: a spindle oil, not a thinned gear oil. Anyone who has standardised a mill on one drum has already paid for this in electricity without seeing it on a maintenance report.
What we can and cannot tell you
What is above is mechanism, and mechanism travels. What does not travel is your specific machine: build year, ambient temperature in the hall, how long between oil changes, what is in the box now. We can tell you why the cam box is different from the slow-speed box. We cannot tell you the right grade for your loom without those four answers, and neither can anyone who quotes you a single oil for the hall.
A weaving hall needs at least three grades. If that sounds like a supplier arguing for a larger order, check the logic rather than the source: the cam box, the worm drives and the spindles fail for three different reasons, and one oil cannot be optimal for all three.
Textile applications → · MOTTA SH Spindle & Hydraulic Oil Series →