Medium duty castors are often mounted into tubular legs. But again, it is important that these legs stay vertical.
We recommend that the leg never extend more than 125 mm below the nearest support, and (apart from the lightest uses), the tube should be 1.4 mm thick or more. Thinner gauges often split. If you wish to use lighted gauge in the rest of the trolley, insert a sleeve for at least 150 mm where the castor is mounted.
Never put a round expanding fitting into a square tube as when the trolley hits a bump, the tube is likely to elongate, and the castor may fall out. We do have square fittings, and ask that you use them. If for some reason you need to put round into square, then weld an insert sleeve of round tube (remember—our smallest fitting needs 3/4” ID). When using Directional Lock (DL) type castors it is best to use the solid swivel stem and weld or bolt it in—screwed types can become misaligned. To achieve the best performance from the larger 175 mm and 200 mm castors use solid stems.
When fitting expanding stem castors, make sure that the fitting is fully inserted into the tube, with the tube firmly down onto the castor head rivet, before tightening it up (you may have to remove some of the burr on the inside of the tube before you try to push the fitting in). After making sure the weld on the inside of the tube is not excessive, align it with one of the slots down the outside of the adaptor fitting. Put the fitting into the tube all the way, then put some sideways pressure on to it to help the fittings grip, then tighten the stem bolt firmly. Do not over-tighten, or you will make it hard to remove later. It is advisable that any tube fitting on expanding stem castors be checked after the first 3 months, and then yearly to make sure the tube fitting is fully and firmly into the tube and the tightening nut is firmly but not over tightened.