McAllister Technical

Manufacturers of surface analytical instruments and devices

                  THANK YOU for your purchase of MTS' Bellows Sealed Linear Translator (BLT). It is the finest of its kind available. We appreciate the confidence you have placed in our company. Under normal conditions your BLT will provide years of trouble-free service, especially if the following simple maintenance is performed:

                  As delivered, the screws and ball bearings are coated with baked-on molybdenum disulfide. This coating will degrade over time, due to moisture in the atmosphere. Re-lubricate the ball bearings every third or fourth bake out with the molybdenum disulfide grease provided with your shipment. Lightly lubricate the screws with the molybdenum disulfide grease after every other bake out. Do not use a hydrocarbon grease such as Felpro C100TM for units that will be baked because the hydrocarbon greases will cake and dry out. Maximum bakeout temperature is 150oC.

                  On the 6-ear models, the chain may stretch with use. This is normal. Should it become necessary to adjust the tension on the chain, first remove the retainer clip and master link from the chain, and then remove the chain from the sprockets. Using a hex wrench, loosen the three socket head screws that hold the bronze idler sprocket bearing around the guide rod. Note that the idler sprocket bearing is eccentric to the guide rod.

Eccentric idler

                  Replace the chain temporarily, using only the master link without the retainer clip. Adjust one or more of the idler eccentrics until the desired tension has been achieved. Tighten the two socket head screws that are not blocked by the chain. Remove the chain and tighten the third screw. DO NOT OVER-TIGHTEN THE SCREWS. Replace the chain.

                  On both the 3-ear and the 6-ear models, the flanges may need to be re-aligned to be parallel after removing or replacing the chain. Should it become necessary to adjust the alignment of the two flanges, first remove the retainer clip and master link from the chain, then remove the chain from the sprockets. Using dial calipers or some other measuring instrument, measure the distance between the two flanges. Adjust the three screws individually so that the flanges are parallel to within 0.005" (0.12 mm). Replace the chain and master link.

Replacing bearings in a BLT:
Cross Section

                  With the BLT off the vacuum system, remove the little screws from underneath (from the vacuum-face side of the chamber flange) that go into the jacking screws, and that go into the guide rods. The guide rods should be able to freely slide out of the eccentrics, even if only a little way. Remove the chain, and tap the jacking screws out of the bearings. The best way to do this is to put a long screw (8-32) in the thread and tap on that screw. This will free the jacking screws from the black ring. Then remove the bolts from around the circumference of the black ring, and slip the ring off of the flange in the direction of where your chamber used to be. With the ring off, remove the 3 screws in the bearing retainer ring and press the bearings out of the black ring, using a plug of plastic or a socket, from the backside. Put the new, greased bearings in the holes. Press them in (they are a very light press fit; they won't be very tight), put the bearing retainer rings back on, and repeat the disassembly operations in reverse order. Finally, adjust the flange parallelism and the tensioning of the chain as detailed above.

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Last Updated: 25 August 2000