SKF TMFT 36 Bearing Fitting Tool Kit, 36 Impact Rings

Fitting bearings by the ring that carries the interference

SKF states that poor fitting, usually with brute force, accounts for 16 % of premature bearing failures. The SKF TMFT 36 kit is designed for quick and precise cold mounting of bearings while minimising the risk of damage. The right combination of impact ring and sleeve passes the mounting force to the bearing ring that has the interference fit, so the force does not travel through the rolling elements and mark the raceways.

The kit contains 36 impact rings, 3 impact sleeves and a dead-blow hammer in a lightweight carrying case. It also suits other components such as bushings, seals and pulleys. Rings are marked for easy size selection, click on to the sleeve for stability, and are made of high impact resistant material. The impact rings can also be used under a press.

Technical specifications

Bearing series the kit covers

SKF lists the following ranges as suitable: deep groove ball bearings 6000 to 6011, 6200 to 6211, 6300 to 6311 and 6403 to 6409 plus small series such as 629, 62/22, 62/28, 63/22, 63/28, 16002 to 16011, 16100 to 16101 and 98203 to 98206; sealed deep groove 62200 to 62211, 62300 to 62311 and 63000 to 63010; self-aligning ball bearings 1200 to 1211, 129, 1301 to 1311, 2200 to 2211, 2301 to 2311 and 11207 to 11210; angular contact ball bearings 7000 to 7011, 7200 to 7211, 7301 to 7311, 3200 to 3211 and 3302 to 3311; spherical roller bearings 21305 to 21311, 22205 to 22211 and 22308 to 22311; cylindrical roller bearings in several N series; tapered roller bearings in the 302, 303, 313, 320, 322, 323, 330 and 332 series within the size ranges printed in the leaflet; and CARB toroidal bearings C 2205 to C 2211, C 4010 and C 6006. For the full list per series, use the leaflet.

Using it correctly

The interference fit should be determined from the SKF catalogue or maintenance handbook. Mount a bearing on the shaft by driving the inner ring, and into a housing by driving the outer ring; where both are tight, use a ring that seats on both. Wear eye protection when striking. See other bearing maintenance tools under Electric Motors. Before ordering, check that your bearings fall inside the bore range and series list.

Choose the ring so that its inner and outer diameters match the bearing, as SKF states that the diameter of the impact ring precisely fits the inner and outer diameter of the bearing. Seat the sleeve squarely, and strike the dead-blow hammer in firm, controlled blows rather than hard ones. Stop when the ring seats against the shoulder. For bearings above 55 mm bore the kit does not apply, and other methods such as induction heating are normally used, so check the size first.

Preparing the shaft and housing before mounting

Clean fitting starts before the first blow. Wipe the shaft seat and housing bore free of grit, old grease and corrosion, and look for burrs or raised edges that would make the ring bind part way on. A light film of oil on the seat helps the ring slide evenly. Measure the shaft and bore against the tolerances given in the SKF catalogue so you know the fit is what the design calls for; a seat that is oversize or out of round will not be corrected by careful tapping. Keep the new bearing in its wrapping until the moment it is fitted, because fine dust that settles on an open bearing ends up in the raceways.

Working in Oman and GCC workshops

Maintenance in the Gulf often happens in open sheds, on site skids or next to running plant, where wind-blown sand and dust are hard to avoid. Set up a clean mat or bench for the kit, close the case between jobs, and wipe each impact ring and sleeve before it touches a bearing. In summer, metal parts left in direct sun get hot to handle and expand slightly, so let shaft, housing and bearing sit together in the shade until they are at a similar temperature before checking fits. In humid coastal sites near the sea, dry and lightly oil any exposed shaft surfaces after fitting so the seat does not start to rust.

Selection checks before you order

List the bearings your team actually replaces and compare each designation with the series list above, paying attention to the bore range and to the maximum shaft length each sleeve can reach over. Where a bearing sits deep on a long shaft, confirm that the sleeve length is enough to reach it. Also note whether the tight ring is the inner ring, the outer ring or both, since that decides which ring and sleeve combination you will use. If a bearing falls outside the kit, plan a different method rather than forcing a near match.

Looking after the kit

After use, inspect the impact rings and sleeves for cracks, chips or deformation, and set aside any part that no longer seats squarely, because an uneven ring will push the bearing on at an angle. Check the hammer head for damage and the handle for looseness. Return every ring to its place in the case so the next technician can find the correct size quickly and nothing goes missing on site. Keep the SKF leaflet with the kit, and record which bearings were fitted on each machine so later maintenance can follow the same method.

Documents and quotation

The SKF leaflet is attached. Send the quantity and delivery point, and the bearing sizes you work with if you want us to confirm coverage.