The CL Type Gear Coupling is a standard crowned-tooth gear coupling per GB/T5843, available in 16 sizes (CL1–CL16) from 40 N·m to 40,000 N·m at up to 4750 RPM, in CL compact and CLZ extended sleeve configurations. With Y, J1, and Z taper bore options, it is well suited for pump, fan, conveyor, compressor, and general industrial drives requiring a reliable, low-maintenance metal coupling with misalignment tolerance.
The standard crowned-tooth gear coupling per GB/T5843 for general industrial drives worldwide. Compact, reliable, and economical — available in CL (standard) and CLZ (extended sleeve) configurations. Factory direct from stock or to custom bore specification.
The CL type gear coupling is a crowned tooth (drum shape) flexible coupling per GB/T5843, designed for general industrial shaft-to-shaft connections across a full range of applications. It is the most widely used gear coupling standard in Chinese industry.
The CL coupling consists of two inner hubs — each with external crowned gear teeth — and a single outer sleeve with internal straight teeth connecting both hubs. The crowned tooth mesh transmits torque while simultaneously accommodating angular, radial, and axial shaft misalignment, protecting motor and gearbox bearings from misalignment-induced loading. Two variants are available: CL (compact standard configuration) and CLZ (with extended outer sleeve for wider shaft gaps), both using the same inner hub geometry and bore specifications.
The key distinction between a CL type crowned tooth gear coupling and a conventional straight tooth gear coupling lies in the geometry of the external teeth on the inner hubs. In a straight tooth gear coupling, tooth flanks are machined flat and parallel to the shaft axis — producing a line contact spanning the full tooth face width. In the CL's crowned tooth design, the tooth profile is barrel-shaped — thickest at its mid-point and tapering toward both ends. This geometry produces a Hertzian contact ellipse near the tooth centre rather than a line contact across the full face.
The practical consequence of this difference is significant: a straight tooth coupling generates contact stress that rises steeply at the tooth edges whenever angular misalignment is present — even small misalignments of 0.1 to 0.2 degrees concentrate the full tooth load at one edge, quickly exceeding the tooth surface fatigue limit. The CL's crowned tooth maintains its contact ellipse near the tooth centre even at angular misalignment of up to 1.5 degrees, distributing load uniformly regardless of shaft angle — eliminating edge loading entirely.
The CL coupling accommodates three types of shaft misalignment simultaneously, each through a different mechanism in the crowned tooth mesh.
Each CL coupling consists of two identical inner hubs (mounting on their respective shafts via parallel keyway bore or taper bore) and a single outer sleeve. The sleeve has internal straight teeth machined on its bore at both ends, each meshing with one inner hub's external crowned teeth to form the two-mesh torque transmission path. A lubrication fill port at the mid-span of the outer sleeve provides access for grease injection. The sleeve is retained on the hubs by the tooth mesh engagement and a seal arrangement at each end.
The CLZ variant uses an extended outer sleeve — longer overall length with the same internal gear tooth geometry at each end — providing a wider shaft gap capability from the same inner hub components. This is equivalent in function to a spacer coupling, allowing the CL hub geometry to be used wherever a longer shaft span is required without changing the inner hub design.
| Feature | CL Type (this product) | Jaw Coupling | Disc Coupling | Straight Tooth Gear Coupling |
|---|---|---|---|---|
| Misalignment Tolerance | High — crowned tooth, up to 1.5 deg | Moderate (elastomer deflects) | Low — disc pack torsionally stiff | Low — edge loading above 0.1 deg |
| Shock Load Tolerance | Excellent — no elastomer to shear | Good (elastomer absorbs, then fails) | Poor — disc pack fatigues rapidly | Poor — edge overload at each shock |
| Torque-to-Size Ratio | High — compact gear mesh | Moderate | Moderate–High | High (but shorter service life) |
| Maintenance | Periodic re-lubrication | Elastomer replacement 1–3 years | Low maintenance (no lube needed) | Periodic re-lube; shorter intervals |
| Torque Range | 40 – 40,000 N·m (CL1–CL16) | Up to ~3000 N·m typically | Wide range | Wide but shorter service life |
Both CL and CLZ use identical inner hubs for the same size number, share the same torque rating, bore range, and speed limit, and are assembled using the same installation procedure. The only structural difference is the outer sleeve length.
| Factor | CL — Standard Compact | CLZ — Extended Sleeve |
|---|---|---|
| Outer Sleeve Length | Standard B dimension per GB/T5843 | Extended B dimension — longer overall assembly |
| Shaft Gap Capability | Standard — motor to machine close-coupled | Wider — spans larger shaft-end gaps |
| Torque Rating | Same as CLZ (same size number) | Same as CL (same size number) |
| Bore Range | Same as CLZ | Same as CL |
| Speed Rating | Same as CLZ | Same as CL — verify critical speed for long sleeves |
| Weight | Lighter — shorter sleeve | Heavier — extended sleeve adds mass |
| Axle Withdrawal | No — shaft must move axially to remove coupling | Limited — longer sleeve allows some access clearance |
| Price | Lower — less sleeve material | Slightly higher — additional sleeve length |
| Choose When... | Standard close-coupled drive; no shaft gap constraint; minimum weight and cost | Wider shaft separation; structural clearance between motor and machine; limited axle access requirement |
All specifications per GB/T5843. Bore diameter range (d min to d max) for Y type cylindrical bores. Maximum bore diameter for Z taper bores is the same as Y type maximum. J1 type bores are available where L engagement length is greater than Y type at the same bore diameter.
| Size | Nominal Torque Tn (N·m) |
Max Speed (rpm) |
Bore Range d (mm) |
Y bore length L range (mm) |
Outer Dia D (mm) |
CL Length B (mm) |
CLZ Length B1 (mm) |
Angular Tolerance |
CL Weight (kg approx) |
|---|---|---|---|---|---|---|---|---|---|
| CL1 | 40 | 4750 | 10–16 | 25–32 | 80 | 60 | 90 | 1.5 deg | 1.2 |
| CL2 | 63 | 4750 | 10–22 | 25–52 | 100 | 72 | 110 | 1.5 deg | 2 |
| CL3 | 100 | 4000 | 12–28 | 25–60 | 120 | 84 | 125 | 1.5 deg | 3.5 |
| CL4 | 160 | 3150 | 16–35 | 32–82 | 145 | 100 | 148 | 1.5 deg | 5.5 |
| CL5 | 250 | 2800 | 20–45 | 42–112 | 175 | 120 | 175 | 1.5 deg | 9 |
| CL6 | 400 | 2500 | 25–55 | 52–142 | 210 | 140 | 205 | 1.5 deg | 16 |
| CL7 | 630 | 2240 | 32–65 | 60–172 | 250 | 165 | 240 | 1.5 deg | 26 |
| CL8 | 1000 | 2000 | 40–80 | 84–212 | 295 | 190 | 280 | 1.5 deg | 42 |
| CL9 | 1600 | 1800 | 50–95 | 107–252 | 350 | 225 | 330 | 1.5 deg | 65 |
| CL10 | 2500 | 1600 | 60–110 | 107–302 | 415 | 265 | 390 | 1.5 deg | 105 |
| CL11 | 4000 | 1400 | 75–130 | 132–352 | 485 | 310 | 455 | 1.5 deg | 165 |
| CL12 | 6300 | 1250 | 90–160 | 172–410 | 570 | 365 | 535 | 1.5 deg | 260 |
| CL13 | 10000 | 1120 | 110–200 | 212–470 | 670 | 430 | 630 | 1.5 deg | 415 |
| CL14 | 16000 | 1000 | 130–240 | 252–550 | 790 | 500 | 735 | 1.5 deg | 650 |
| CL15 | 25000 | 900 | 160–280 | 302–650 | 930 | 585 | 860 | 1.5 deg | 1030 |
| CL16 | 40000 | 800 | 190–320 | 352–750 | 1090 | 680 | 1000 | 1.5 deg | 1600 |
Note: Weight values are approximate, based on maximum bore Y type. Bore ranges shown are for Y type; J1 type bores use the same bore diameter range with increased engagement length L. Z taper bores (1:10) are available up to the maximum bore diameter shown. CLZ B1 length values indicate the extended sleeve variant. All torque ratings are nominal (Tn); multiply by 1.25 for peak torque check in the selection calculation.
Custom Bore, Non-Standard Engagement Length, and CL/CLZ Available Together
Any bore diameter within the range for the chosen CL size can be machined to your shaft drawing — including metric IEC motor shaft sizes (14, 19, 24, 28, 38, 42, 48, 55, 60, 65, 75, 80 mm and above). Both CL and CLZ sleeves can be ordered for the same pair of inner hubs, allowing future sleeve exchange if the shaft gap changes. Send your shaft drawing or motor frame size for a confirmed bore specification.
Every industrial drive experiences shock loads — conveyor belt starts under load, compressor pressure build-up, mixer blade contact with oversize material, and pump cavitation events all generate torque spikes of 2–4× running torque. The CL's crowned teeth distribute these peaks as Hertzian contact ellipses at the tooth flank centre, with no edge stress concentration.
CL couplings require periodic re-lubrication (every 6–12 months) and periodic tooth wear inspection — but no consumable elastomers, no disc pack replacement, and no wear-induced misalignment. The typical CL coupling replacement interval in a well-lubricated, correctly aligned installation is 5–10 years in standard industrial duty, compared to 1–3 years for jaw couplings and 2–5 years for disc pack couplings in the same duty.
CL1 through CL4 are rated to 4750 and 3150 RPM respectively — fully compatible with 2-pole IEC motors. For applications above 2500 RPM, the coupling must be balanced to ISO 1940/1 Grade G6.3 or better, and the bore fit should be H7/k6 to ensure concentricity. The CL's metal-only construction means there is no speed-dependent degradation from centrifugal loading on flexible elements, unlike jaw couplings at high speed.
CL inner hubs are manufactured from forged steel blanks — 45# carbon steel for smaller sizes (CL1–CL8) and 42CrMo4 alloy steel for larger sizes (CL9–CL16). The outer sleeves are machined from seamless alloy steel tube or forged rings depending on size. Crowned teeth are CNC hobbed to GB/T10095 Class 8 accuracy. Tooth flanks are either induction hardened (CL1–CL10) or carburised and quench hardened (CL11–CL16) to HRC 50–58 surface hardness with HRC 28–35 core hardness.
All bores are finish-machined after heat treatment to H7 tolerance using CNC boring or grinding. Keyways are broached to JS9 tolerance. Z type taper bores (1:10) are verified with taper plug gauges and blue contact checks for minimum 75% contact before acceptance.
ISO 9001:2015 quality management certification covers the full CL/CLZ manufacturing process. CE marking is applicable to relevant export sizes. Products manufactured per GB/T5843. Every shipment includes material mill certificates with heat traceability, heat treatment records, Rockwell hardness test certificates, and dimensional inspection reports.
CL couplings are available from a single replacement unit to full project quantities for new-build plant with multiple drives. Standard bore combinations from CL1 to CL12 are held in stock. Custom bore dimensions and CL13–CL16 ship within 10–15 working days. For project quantities of 20 or more identical units, contact our team for project pricing and scheduling.
CL inner hubs and outer sleeves are available as individual components, not only as matched pairs. This allows you to replace a worn outer sleeve without replacing the shaft-mounted hubs, or to order a CLZ sleeve for an existing CL hub pair when the shaft gap changes. Request component pricing here.
RP supplies CL and CLZ alongside the WG, WGP, WGC, WGZ, WGT, DC, and other coupling families. Projects mixing CL couplings on standard drives with WG or WGT on specialised drives are served by one engineering team, one documentation set, and one shipping event.
Customer Profile: A food processing facility operating 24 belt conveyor drives rated 11–37 kW on a chilled product handling line, with couplings exposed to frequent cleaning wash-down and high humidity. Original jaw type elastomeric couplings averaged 14 months replacement interval due to elastomer degradation from wash-down chemicals and low-temperature operating environment.
Challenge: Jaw coupling elastomers were degrading within 12–16 months from repeated wash-down with alkaline cleaning solution at 60°C, creating coupling backlash that caused product registration errors on the line. The maintenance manager needed a coupling with no elastomers, tolerance of wet and chemical environments, and equivalent shock absorption capability.
Solution: We supplied 24× CL couplings in sizes CL5 to CL8 (250–1000 N·m) with food-grade grease pre-fill and stainless steel hardware for the fill port assembly. The CL's gear mesh requires no elastomers and is unaffected by wash-down chemicals, which are sealed from external contamination by the sleeve end seals.
Result: 31 months since installation with zero coupling replacements across all 24 drives. The product registration errors caused by jaw coupling backlash were eliminated from the first installation. Annual coupling maintenance cost for the 24 drives reduced by approximately USD $36,000.
Customer Profile: A packaging operation with 8 blister pack machines from a Chinese OEM, each with 3 CL couplings per machine (CL4, CL5, and CL6 in different drive positions) requiring replacement after 4 years of production operation.
Challenge: The maintenance team had the original machine documentation showing coupling sizes as "CL4, CL5, CL6 per GB/T5843" but no bore dimensions. Three local coupling suppliers had been unable to cross-reference the GB/T5843 standard and had quoted incorrect bore sizes that would not have fitted the existing shafts.
Solution: We confirmed the CL4 bore at 28 mm, CL5 bore at 35 mm, and CL6 bore at 45 mm from the machine shaft drawings, and supplied 24× replacement couplings (8 machines × 3 sizes) with confirmed bore specifications and keyway dimensions matched to the original machine shafts.
Result: All 24 replacement couplings installed correctly on first attempt — zero rework or remachining. The maintenance manager has since placed repeat orders for the same coupling combinations at each 4-year machine service interval.
Customer Profile: A gold mine operating 6 underground ventilation fans rated 75 kW each, with motor-to-fan shaft spans requiring CLZ configuration due to fan bearing housing standout.
Challenge: Existing fan drives used flexible disc coupling sets that were fatigue-failing within 18 months under combined shock loading from fan blade imbalance events and the frequent starts and stops of underground ventilation scheduling. Each disc coupling failure triggered a mandatory production hold — typically 6–8 hours.
Solution: We supplied 6× CL9 CLZ couplings (1600 N·m, d=65 mm, with CLZ extended sleeve to match the existing fan bearing housing standout of 280 mm). The CL9's crowned tooth shock tolerance was confirmed by calculation to handle 3× rated torque peaks from fan blade imbalance events.
Result: Zero coupling failures across all 6 fans in 30 months since installation — versus 2 failures per fan per 18-month period with the previous disc couplings. At an estimated 8-hour production hold per failure event with 10 expected failures avoided, the CL upgrade prevented approximately 80 hours of ventilation-related production delays.
The CL type gear coupling is a crowned tooth (drum shape) flexible coupling per GB/T5843. It consists of two inner hubs with external crowned teeth and a connecting outer sleeve with internal straight teeth. The crowned tooth geometry transmits torque while accommodating angular, radial, and axial shaft misalignment without edge loading. CL covers 16 sizes from CL1 (40 N·m, 4750 rpm) to CL16 (40,000 N·m, 800 rpm). CLZ is the extended sleeve variant for wider shaft spans.
The design torque Td = T × Ks, where T is the nominal running torque (calculated from motor power and speed: T = 9550 × P/n) and Ks is the service factor (1.25–2.5 depending on drive type and duty class). choose the CL size where the nominal torque Tn ≥ Td. For shock loading applications, multiply by a shock factor of 1.5–2.5 before comparison. Our engineering team performs this calculation for every order as a standard service.
CL and CLZ use identical inner hubs for the same size number, with the same torque rating, bore range, and speed limit. The only difference is the outer sleeve length — CLZ has an extended sleeve that spans a wider shaft gap. Choose CL for standard close-coupled drives; choose CLZ when the motor and machine shaft ends are further apart than the CL sleeve can bridge in its standard B dimension.
Re-lubricate through the fill port at the mid-span of the outer sleeve at 6–12 month intervals using lithium complex grease (NLGI Grade 2) or EP gear oil. Inject grease until it emerges from the vent port or the opposite fill hole, confirming both tooth mesh zones are filled. Purge old grease from the vent port before re-filling to avoid over-pressure in the sleeve cavity.
Yes, on CL couplings where the shafts can be moved axially by the sleeve length B (or B1 for CLZ). The standard CL disassembly procedure is to slide one shaft axially to produce clearance, slide the sleeve off the first hub, and then return the shaft to position. For CLZ couplings with extended sleeves, the required axial shaft movement is reduced.
CL per GB/T5843 and GICL per JB/T8854.3 are both crowned tooth gear couplings with similar application intent, but their dimensional geometry differs — they are not directly interchangeable without checking bore, outer diameter, and coupling length. If you need to substitute CL for GICL or vice versa, provide both coupling size numbers and bore data to our team for a confirmed dimensional compatibility check before ordering.
Send us your coupling size (CL1–CL16), bore diameter, keyway dimensions, and CL or CLZ sleeve requirement. If you only have the motor power and speed, our engineering team will choose the correct size for you. Factory-direct quotation within 24 hours — with full bore specification confirmation and documentation package.
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