Taper bushes and shaft lock nuts are the two dominant hub-anchoring methods on 2026 power-transmission drawings, but they fix different failure modes and cost different amounts to install and to remove [S1].
A taper bush is a flanged split sleeve with a 1.5°-8° taper wall, driven onto a mating hub by tightening 2-4 axial cap screws; published sizes run from 1008 (9-25 mm bore) through 5050, and current retail part pricing for a 1108-1" bushing is around GBP 4.96 (≈ USD 6.30) on the used market [S1][S2]. A lock nut — properly a precision shaft nut with a locking feature — threads onto a shaft-end or adapter sleeve, with popular metric threads M10-M100 and typical tightening torques stamped on the bearing datasheet.
Operating Principle and Mechanical Behaviour
A taper bush relies on a wedging action: tightening 2-4 axial cap screws (commonly 5/16" UNC on 1108, 3/8" UNC on 1610-2510, 1/2" UNC on 3020-5050) forces the bush's split taper into the hub taper, expanding the bush onto the shaft with a contact pressure that typically peaks at 80-150 MPa near the large end of the taper. Removal is the inverse — slacken the screws and the bush walks off the shaft with a tap. [S1]
A lock nut transmits torque through a thread interface: tightening to a stamped torque (e.g. 34 N·m for an M20 precision nut, 145 N·m for M40) clamps an inner ring or sleeve axially, generating 0.05-0.20 mm of axial preload that locks the rotating element to the shaft via friction. Unlike the taper bush, the lock nut adds no radial preload and cannot compensate for shaft-to-bore clearance greater than the nut's axial stiffness allows.
Size Coverage and Mounting Footprint
Published taper-bush series — 1008, 1108, 1210, 1610, 2012, 2517, 3020, 3535, 4040, 5050 — cover shaft bores from 9 mm to 125 mm, with 1008 alone spanning 9 mm, 10 mm, 11 mm, 12 mm, 14 mm, 16 mm, 18 mm, 19 mm, 20 mm, 22 mm, 24 mm and 25 mm in the metric catalogue [S2]. The same bushing fits any hub in that series, which is why 1108 is sold as a generic TL P24-8M-30 timing-belt pulley mount at USD 65.00 retail [S3].
Lock nuts cover a similar bore range but split it across many thread sizes and locking styles: KM series for adapter sleeves, KMFE for dismounting slots, KML lock-washer types, and N-AN brass-tab variants. A single 30 mm shaft, for example, can be specified with M30×1.5, M30×2, or a 1-1/4"-12 UN fine thread depending on the bearing supplier convention, and the lock-nut face width runs 11-22 mm versus 22-90 mm for taper-bush flanges [S1][S2].
Comparison on Four Decision Criteria
On four buying-relevant criteria, the two systems line up as follows. <strong>Cost per hub:</strong> a 1108-1" taper bush lists at GBP 4.96 (≈ USD 6.30) [S1] and a 2517 cast-iron sleeve runs USD 5.00-12.00 on Alibaba [S5][S6]; a comparable precision lock-nut + washer pair from a premium bearing brand typically costs USD 8-25. <strong>Mounting time:</strong> one Allen-key pass against 2-4 cap screws on the bush (≈ 3-5 min) versus a torque-wrenched nut on a stamped torque (≈ 1-2 min) plus a locking-tab bend if applicable. <strong>Re-usability:</strong> a taper bush can be removed and re-installed 5-20 times before thread wear on the cap-screw holes; a lock nut is single-shot if a locking tab is bent, near-unlimited if a nylon insert or wedge-locking system is used. <strong>Shaft hardness requirement:</strong> both work on a 200-300 HB shaft, but taper bushes tolerate a softer 150 HB shaft better because the wedging pressure distributes over the full taper length rather than concentrating at a thread lead.
Where shaft collars provide only axial position reference, taper bushes and lock nuts both provide torque transmission — the question is whether you need radial-expansion clamping (bush) or axial-friction clamping (nut). When a pillow block bearing sits next to the hub, the lock nut's stamped torque gives a more reproducible preload on the bearing inner ring than a hand-tightened set screw on a bush flange.
Use-Case Fit on Real Drawings
Taper bushes dominate conveyor-head pulleys, fan hubs, and small sprockets because the bushing lets the same hub fit several shaft sizes — a 2517 bushing accepts 16-65 mm shafts — which collapses SKU count in a conveyor-builder's parts room. Standardisation is the economic case: 1008/1108/1210/1610/2012 cover ≈ 80% of sub-50 mm shaft applications in light-industrial power transmission [S2].
Lock nuts dominate where the bearing manufacturer has engineered the shaft as a complete system: tapered-bore spherical roller bearings on SN/SNK housings, adapter-sleeve assemblies (H2308-H2356), and high-speed cylindrical-bore arrangements above ≈ 6000 rpm where the nut's balanced mass distribution matters. They also win where frequent re-positioning is needed — jacking the nut 1-2 mm on the thread moves the bearing axially without splitting a hub. Browse the 3020/3535/2517 family on a Wholesale 3020 3535 2517 Taper Lock Bush product page to see the size ladder a typical conveyor OEM carries.
Failure Modes and Limits
The two systems fail in different ways. Taper bushes fail by hub-bore elongation (the wedging force permanently stretches the hub bore by 0.05-0.15 mm after 1000 thermal cycles above 150 °C), cap-screw thread galling when re-used with non-OEM screws, and fretting corrosion at the shaft-bush interface if the shaft is below 150 HB. [S2]
Neither system is rated for infinite-life slip: both require a key for positive anti-rotation in Class I fits. A 1108-1" bushing with a 1/4" square key accepts roughly 11-22 N·m of slip torque before the key takes over; without the key, a 1108 will slip on a 200 HB shaft at ≈ 18 N·m of torque [S1].
Sourcing, Standards and Materials
Material of construction is grey cast iron (Grade 20-30) for the bulk of commercial taper bushes, with ductile-iron and carbon-steel variants available for impact-loaded applications [S6]. A separate category of ductile-iron bushes is the high-impact 3030-60 cast-iron sleeve shown on Alibaba at USD 5.00+ per piece [S5]. Lock nuts are typically carbon steel (C45, 42CrMo) with zinc plating or black oxide; stainless A2-70 variants exist for food-grade lines.
China-based suppliers dominate the taper-bush supply chain: 1 verified manufacturer and 3 product SKUs showed up on the 2026-05-11 Made-in-China directory query, with hubs including roots blowers and turbo blowers in their core mix [S4]. The metric 1008 size is a global stocking item at GBP 6.25 (≈ USD 7.95) with 99.9% positive feedback on eBay retail channels [S2]. For lock nuts, OEM supply is concentrated in bearing brands (SKF, FAG, NSK, Timken) that ship the nut as part of the bearing datasheet package, not as a stand-alone component.
When to Use Which — 2026 Specifier Rules
Specify a taper bush when the hub bore is below 125 mm, the application is sub-1500 rpm, the shaft may need to be re-sized in the field, and the designer wants one hub drawing to accept several shaft diameters. Specify a lock nut when the bearing manufacturer has engineered the shaft system, the speed exceeds 3000 rpm, the application needs adjustable axial preload, or the housing arrangement already uses an SN/SNK plummer block with an adapter sleeve. [S3]
Both systems can coexist on the same shaft — for example, a 2517 taper bush on a conveyor-head pulley (mounting the hub) plus an M30 precision lock nut on the inboard bearing (preloading the bearing) — and that combination is common on drives feeding a planetary reducer.
Trackable signal: the 1108-1" bushing price moved from GBP 4.96 in early 2025 to roughly the same band in early 2026 on retail marketplaces, with USD-denominated 2517 hubs stable in the USD 5.00-12.00 range on Alibaba listings dated 2026-05-09 [S1][S5][S6]. Another signal: 1008 metric bore coverage expanded to include 24 mm and 25 mm options in the 2025-04 retail catalogues, a 2 mm jump over the previous 22 mm ceiling [S2].
For component-level specifications, see pressure transmitter.