Tom Bishop, PE
EASA Senior Technical Support Specialist
There are two types of pulleys that will be addressed in this article: quick detachable (QD) and taper lock. Instructions for installing and removing both types will be provided. A note about terminology: There are some that have differing definitions for pulley and sheave. However, in this article we consider the terms to be synonymous and will use the term “pulley”.
QD (Quick Detachable) Type Pulley Installation and Removal
Instructions for installing QD type pulleys
Clean the shaft, bushing bore, bushing barrel and the pulley hub bore of all oil, paint and dirt. Remove any burrs with a file or emery cloth. Note: Lubricants are not to be applied to bushings or pulleys.
Next, determine whether conventional or reverse mounting will be used (See Figure 1).
Instructions for conventional mounting are as follows.
- Insert the key into the shaft keyway. If a key is furnished with the bushing, the key is special and must be used.
- Insert a screwdriver blade (or similar tool) into the bushing flange saw cut to enlarge bore slightly. Caution: Excessive enlargement can split the bushing.
- Slide bushing onto shaft with the flange side towards the equipment. Position bushing and tighten set screw enough to prevent sliding on shaft.
- Place the pulley onto bushing and insert cap screws. Align drilled holes in pulley hub with tapped holes in bushing flange. Install M through S style bushings (See Table 1) so that the two tapped removal holes in pulley hubs are located as far away as possible from the bushing saw cut. Finger-tighten the screws.
- Proceed to the section on completing the installation.
Instructions for reverse mounting are as follows.
- Insert the key into the shaft keyway. If a key is furnished with the bushing, the key is special and must be used.
- Place pulley onto shaft without bushing.
- Insert a screwdriver blade (or similar) into the bushing flange saw cut to enlarge bore slightly. Caution: Excessive enlargement can split the bushing.
- Slide bushing onto shaft with flange facing outward, away from equipment. Position bushing and tighten the set screw enough to prevent sliding on shaft.
- Place the pulley onto the bushing and insert cap screws. Align drilled holes in bushing flange with tapped holes in pulley hub. Install M through S style bushings (See Table 1) so that the two tapped removal holes in pulley hubs are located far away from the bushing saw cut. Finger-tighten the screws.
- Proceed to the section on completing the installation.
Instructions for completing the installation
- When positioned to the desired location, secure the first pulley/bushing assembly to the shaft by tightening the bushing cap screws.
- Allow for small axial pulley movement on bushing during tightening.
- Using a torque wrench, tighten the cap screws evenly in an alternating pattern until the recommended torque level in Table 1 is reached.
- When mounting pulleys on vertical shafts, precautions must be taken to prevent the pulley/bushing from falling during the tightening.
- Caution: Do not continue tightening cap screws further after target torque has been reached as bushing over-insertion and hub fracture may occur. The gap between the bushing flange and pulley hub is intentional and necessary.
Instructions for removing QD type pulleys
- Release belt tension and lift belts off the pulley. Do not pry or roll belts off the pulley.
- Loosen and remove cap screws securing pulleys to bushings. If applicable, loosen keyway set screws.
- Insert cap screws into the tapped removal holes adjacent to the drilled holes.
- Alternately tighten cap screws in small but equal increments until pulley disengages from bushing. Uneven or excessive pressure on cap screws can break bushing flanges making removal extremely difficult.
- The pulley and bushing can now be removed from the shaft.
Taper lock Type Pulley Installation and Removal
Preparation
Clean the shaft, bushing bore, bushing barrel and the pulley hub bore of all oil, paint and dirt. Remove any burrs with a file or emery cloth. Note: Lubricants are not to be applied to bushings or pulleys.
Step-by-step instructions:
- Look at the bushing and the hub (Figure 2) and note that each has a set of half-holes. The threaded holes in the hub are the mates to the non-threaded holes in the bushing.
- Insert the bushing in the hub and slide it onto the shaft.
- Align a threaded hub hole with non-threaded bushing hole.
- Start the setscrews into the holes that are threaded in the hub only. Do not tighten the setscrews yet.
- Align both edges of the pulley with the edges of its mating pulley.
- Tighten the screws alternately and evenly. This procedure will wedge the bushing inward and cause it to contract evenly and grip the shaft.
Step by step instructions for removing taper lock pulleys
- Remove all the setscrews.
- Place two of the setscrews in the holes that are threaded in the bushing only.
- Turn the setscrews alternately and evenly. This movement will unlock the grip and permit easy removal of the assembly with no shock to the bearings or machinery.
AVAILABLE IN SPANISH
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