QD Bushings (Quick Disconnect)
Sizes: SH, SDS, SD, SK, SF, E, F, J, M, N, P, W, S
Bore Range: 3/8" to 12"+ (English); metric bores available
Materials: Cast iron, ductile iron, steel
Keyway: Standard on all sizes (with set screw)
Brands: Gates, Continental/ContiTech
In Stock: Same-day shipping from Houston
QD (Quick Disconnect) bushings are the standard shaft-mounting system for industrial V-belt sheaves and many timing belt sprockets in North America. The tapered, split design locks a sheave or sprocket onto a shaft using cap screws, and reverses for removal without pullers. This two-piece system (bushing + sheave/sprocket sold separately) is what makes QD the preferred choice for industrial drives: one sheave can fit many different shaft sizes by simply swapping the bushing.
Texas Belting stocks QD bushings in all 13 standard letter sizes, covering bore diameters from 3/8" up to 12" and beyond. English bores with keyway and set screw are standard. Metric bores are available for most sizes.
QD Bushing Size Guide
The QD bushing letter size is determined by your sheave or sprocket. The sheave/sprocket part number or hub markings specify which bushing letter it accepts. Once you know the letter size, select the bushing with the bore diameter that matches your shaft.
| Size | Bore Range & Typical Use |
|---|---|
| SH | 3/8" to 1-1/8". Smallest QD. Light duty A and 3V sheaves, small timing sprockets. 2 cap screws. |
| SDS | 1/2" to 1-5/8". Most common small QD. A and B sheaves, 3V sheaves, small 5M sprockets. 2 cap screws. |
| SD | 1/2" to 2-1/8". Medium duty. B, C, 5V sheaves, 5M and 8M sprockets. 2 cap screws. |
| SK | 3/4" to 2-7/16". Medium to heavy. B, C, 5V sheaves, 8M sprockets. 2 cap screws. |
| SF | 3/4" to 3-3/16". Heavy duty. C, D, 5V, 8V sheaves, large sprockets. 3 cap screws. |
| E | 1" to 3-15/16". Heavy industrial. C, D, 8V sheaves, 8M and 14M sprockets. 3 cap screws. |
| F | 1-3/16" to 4-15/16". Large bore. D, E sheaves, Poly Chain sprockets, heavy conveyors. 3 cap screws. |
| J | 1-7/16" to 5-15/16". Very large. D, E sheaves, mining and aggregate equipment. 3 cap screws. |
| M | 2-1/16" to 7-7/16". Extra large. Heavy industry. 3 cap screws. |
| N | 2-15/16" to 8-15/16". Large plant equipment. 3 cap screws. |
| P, W, S | Up to 12"+. Largest QD sizes for extreme heavy-duty drives. Mining, paper, steel mills. 3+ cap screws. |
Metric bores are available in most QD sizes. Specify the shaft diameter in millimeters when ordering and we will confirm availability.
How to Order a QD Bushing
You need two pieces of information:
1. Bushing letter size. This comes from your sheave or sprocket. Check the part number, product listing, or hub markings. Example: a sheave marked "SD" accepts an SD bushing.
2. Bore diameter. Measure your shaft diameter. Standard bores include keyway and set screw. Example: SD x 1-1/8" means an SD bushing with a 1-1/8" bore.
The complete bushing part number combines the letter and bore: "SD x 1-1/8" or "SDS x 3/4" or "SK x 1-7/16". If you are not sure which size your sheave requires, send us the sheave part number and we will confirm the correct bushing.
Installation
Step 1: Clean the shaft, bushing bore, and hub taper surfaces. Remove all dirt, rust, burrs, and old lubricant.
Step 2: Place the bushing into the sheave or sprocket hub with the cap screw holes aligned. The bushing should slide in by hand.
Step 3: Slide the assembly onto the shaft and position it at the correct location for belt alignment.
Step 4: Insert the cap screws into the tapped holes. Tighten alternately in small increments (quarter turns) until all screws reach the specified torque.
Step 5: After a few hours of operation, re-check and re-torque all cap screws.
Removal
Step 1: Loosen and remove all cap screws.
Step 2: Thread the cap screws into the push-off (jacking) holes in the bushing flange. These are the unthreaded holes that were empty during installation.
Step 3: Tighten the cap screws alternately. They will push the bushing out of the hub taper, releasing the grip on the shaft.
Step 4: Slide the bushing and sheave/sprocket off the shaft.
No pullers, hammers, or special tools are needed. This push-off removal is the key maintenance advantage of the QD system over fixed-bore and press-fit designs.
Recommended Cap Screw Torque
| QD Size | Torque (ft-lbs) |
|---|---|
| SH | 6 ft-lbs |
| SDS | 8 ft-lbs |
| SD | 15 ft-lbs |
| SK | 15 ft-lbs |
| SF | 30 ft-lbs |
| E | 50 ft-lbs |
| F | 50 ft-lbs |
| J | 75 ft-lbs |
| M | 100 ft-lbs |
| N | 150 ft-lbs |
| P, W, S | Varies. Refer to manufacturer specs for the specific size. |
Brands We Carry
| Brand | Products |
|---|---|
| Gates | Full range of QD bushings in all letter sizes. English and metric bores. Cast iron and ductile iron. Industry standard. |
| Continental | QD bushings for industrial replacement. English and metric bores. Compatible with all standard QD sheaves and sprockets. |
QD bushings are interchangeable across brands. A Gates QD bushing will fit a Continental sheave (and vice versa) as long as the letter size and bore match. We cross-reference between Gates, Continental, Browning, Martin, Dodge, and other manufacturers. Send us any part number and we will confirm the match.
Related Pages
Frequently Asked Questions
What does QD stand for?
QD stands for Quick Disconnect. It describes the bushing's ability to be quickly installed and removed using cap screws, without pullers or special tools. The cap screws pull the bushing in during installation and push it out during removal.
How do I know which QD bushing size I need?
The QD bushing letter size is determined by the sheave or sprocket, not the shaft. Check the sheave/sprocket part number, product listing, or hub markings for the letter designation (SH, SDS, SD, SK, SF, E, F, J, M, N, P, W, or S). Then select the bushing with that letter and the bore diameter matching your shaft. If you are unsure, send us the sheave part number and shaft diameter.
Are QD bushings interchangeable between brands?
Yes. QD bushings are an industry standard with consistent taper angles and bolt patterns across manufacturers. A Gates SDS bushing will fit a Continental SDS sheave, a Browning SDS sheave, and so on. The letter size and bore must match, but the brand does not have to match between bushing and sheave.
Can I use a QD bushing on a Taper Lock sheave?
No. QD and Taper Lock are different systems with different taper angles, bolt patterns, and mounting geometries. A QD bushing will not seat correctly in a Taper Lock hub and vice versa. The bushing system must match the sheave or sprocket hub.
Should I lubricate the QD bushing taper?
No. QD bushings rely on dry friction between the bushing and hub taper surfaces to grip. Applying oil, grease, or anti-seize reduces this friction and can cause the bushing to slip under load. Clean both taper surfaces with solvent before installation. This is the opposite of Taper Lock bushings, which require a light oil film.
Are metric bore QD bushings available?
Yes. Most QD bushing sizes are available with metric bores. Specify your shaft diameter in millimeters when ordering. Metric bores include a metric keyway. Contact us to confirm availability for your specific size and bore combination.
How often should I re-torque QD bushing cap screws?
Re-torque after the first 2 to 4 hours of operation on a new or reinstalled bushing. After that, check torque during routine maintenance intervals. Vibration, thermal cycling, and shock loads can cause cap screws to loosen over time. A loose bushing allows the sheave to shift on the shaft, causing belt misalignment, tracking problems, and accelerated wear.
Can Texas Belting cross-reference QD bushing part numbers?
Yes. We cross-reference between Gates, Continental, Browning, Martin, Dodge, and other manufacturers. Since QD is an industry standard, cross-referencing is straightforward. Send us the part number or call 888-203-2358.
