Fenner Industrial Motion H1253 B-LOC Shrink Disc 125-30

Fenner splits these into internal and external devices. Trantorque and B-LOC bushings are internal, fitting between shaft and bore. Trantorque uses a single hex nut and reaches 3 in (75 mm) shafts; B-LOC uses several screws and approaches 24 in (600 mm). Fenner's technical team usually recommends Trantorque up to 1-1/2 in and B-LOC above that. Shrink discs and compression hubs are external. Shrink discs suit standard coupling hubs, flanges and hollow-shaft gearbox outputs, while compression hubs suit narrow components such as plate sprockets. For a small OD to ID ratio consider B800 or Trantorque OE; for very high torque, double taper B112 or B115.

For keyless bushings Fenner recommends 32 to 125 micro-inch (0.8 to 3.2 micrometer) RMS on shaft and hub bore; compression hubs use the same range on the shaft. Turned, ground and polished stock is too smooth and can cause failure, so roughen it lengthwise with a file or emery paper. Tolerance varies by series: plus or minus 0.003 in on Trantorque GT and OE, 0.0015 in on Mini and 0.001 in on B-LOC B109, while B103 shafts are +0/-0.002 in on bores up to 4.724 in. Shrink discs instead set a maximum clearance between shaft and hub bore, from 0.025 mm on small shafts.

It depends on the family. Trantorque: install as received, add no lubricant, and clean shaft and bore to bare metal with a non-petroleum solvent such as isopropyl alcohol. B-LOC bushings and compression hubs: these come lightly oiled, and the screws, tapers, shaft and bore should be clean and lightly oiled with no molybdenum disulfide. Shrink discs: these come with molybdenum disulfide on the tapers and screws; oil the hub OD lightly but clean all lubricant from the shaft and hub bore, because it greatly reduces torque capacity. On every family, do not use anaerobic adhesives such as Loctite or Permatex.

Trantorque: hand tighten the single nut, then use a torque wrench to the listed torque, for example 125 ft-lb on a 1 in GT. Over-tightening can damage the unit. At full torque GT and OE travel about 0.075 in along the shaft, Mini about 0.045 in and NT not at all. B-LOC devices: set the wrench about 5 percent above the listed torque, tighten screws in quarter turns over several passes, add one or two passes once quarter turns stop, then reset to listed torque and check that no screw turns. B103 moves about 0.032 in; B106, B112, B115 and B400 do not. Never tighten shrink disc screws before fitting the shaft.

Fenner's Metals catalog lists part numbers in size tables and prints a key only for compression hubs, where BCH502100-025 is base BCH502100 (BCH50, 1 in shaft) plus 25 mm screws. Elsewhere, check your number against the table. B-LOC numbers usually show series, unit and size: B122400 is a B112 for 4 in, B122615 for 6-15/16 in, and B401050 a B400 for 50 mm. Fenner says the third digit on every B-LOC number gives the unit, 1 for metric and 2 for inch. B800 numbers vary, such as T8012 (12 mm) and T82206 (2-3/8 in). Shrink disc B0301 is size 30-10, in SD10 standard duty. TTQM2235 is a Trantorque OE for a 22 mm shaft and 35 mm OD; EN, DC and SS mean nickel plated, chrome coated and stainless, and UP on a Trantorque GT means un-plated, shipped lightly greased.