15T Roller Chain Idler Sprocket for 3/4″ Pitch ANSI 60 Chain Drives
This 15-tooth roller chain idler sprocket is machined for 3/4-inch pitch ANSI 60 chain systems. Made from C45 carbon steel with induction-hardened teeth (45-52 HRC), it maintains proper chain tension and guides routing in agricultural balers, grain conveyors, and industrial manufacturing equipment. Outside diameter 99.8 mm, pitch circle diameter 91.63 mm, standard bore 12 mm.
15T Roller Chain Idler Sprocket for Reliable Chain Drive Performance
Precision-machined 15-tooth roller chain idler sprocket engineered for 3/4-inch pitch chain systems. Maintains correct chain tension, eliminates slack-induced vibration, and extends drivetrain service life in agricultural, industrial, and material handling equipment.
The Function of a Roller Chain Idler Sprocket in Power Transmission
In any roller chain drive system, maintaining correct chain tension is the difference between consistent power delivery and premature component failure. A roller chain idler sprocket serves as the tensioning element positioned on the slack side of the chain loop. As chains elongate through normal wear—typically 1.5% to 3% over their service life—the idler sprocket absorbs this slack, preventing chain whipping, tooth skipping, and uneven load distribution across drive and driven sprockets.
This steel 15 tooth roller chain idler sprocket is machined from C45 medium carbon steel bar stock, not cast. The teeth are cut on CNC hobbing equipment to ANSI B29.1 tooth profile standards, then induction-hardened to 45-52 HRC at the contact surfaces while maintaining a tough 18-22 HRC core. This dual-hardness structure delivers wear resistance where the chain rollers make contact, combined with shock absorption capacity in the sprocket body where impact loads concentrate during start-up and load changes.
The 15-tooth configuration provides a pitch circle diameter of 91.63 mm with 3/4-inch pitch chain—a common specification in agricultural balers, combine headers, and industrial conveyors where space constraints require compact sprocket diameters while maintaining sufficient tooth engagement for reliable operation.
Technical Specifications of Roller Chain Idler Sprocket
| Parameter | Specification |
|---|---|
| Product Type | Roller Chain Idler Sprocket |
| Number of Teeth (Z) | 15 |
| Chain Pitch | 3/4 inch × 7/16 inch (ANSI 60) |
| Outside Diameter (de) | 99.8 mm |
| Pitch Circle Diameter (dp) | 91.63 mm |
| Tooth Width (A) | 11.1 mm |
| Hub Diameter (D1) | 16 mm |
| Hub Width (F) | 40 mm |
| Bore Diameter (B) | 12 mm (Standard) |
| Keyway Width (H) | 18.3 mm |
| Material | C45 Medium Carbon Steel |
| Tooth Hardness | 45-52 HRC (Induction Hardened) |
| Core Hardness | 18-22 HRC |
| Surface Treatment | Black Oxide or Zinc Plated |
| Manufacturer | China Fidel Group |
Note: Standard bore is 12 mm. This 3/4 inch bore roller chain idler sprocket configuration accepts custom bore sizes from 10 mm to 25 mm with modified keyway dimensions. Contact our engineering team with your shaft diameter requirements. Complete dimensional data for the full product range covering pitch sizes from 3/8 inch to 1-1/4 inch is available in the specification table below.
Complete Roller Chain Idler Sprockets Range
This 15T sprocket belongs to a comprehensive range of roller chain idler sprockets manufactured by China Fidel Group. All configurations share identical material specifications and heat treatment standards:
| Z | Pitch | de (mm) | dp (mm) | A (mm) | D1 (mm) | F (mm) | B (mm) | H (mm) |
|---|---|---|---|---|---|---|---|---|
| 15 | 3/4″×7/16″ | 99.8 | 91.63 | 11.1 | 16 | 40 | 12 | 18.3 |
| 23 | 8×3 | 62.15 | 58.75 | 2.8 | 16 | 40 | 12 | 18.3 |
| 21 | 3/8″×7/32″ | 68.0 | 63.90 | 5.3 | 16 | 40 | 12 | 18.3 |
| 18 | 1/2″×1/8″ | 78.9 | 73.14 | 3 | 16 | 40 | 12 | 18.3 |
| 18 | 1/2″×3/16″ | 78.9 | 73.13 | 4.5 | 16 | 40 | 12 | 18.3 |
| 13 | 3/4″×7/16″ | 87.5 | 79.59 | 11.1 | 16 | 40 | 12 | 18.3 |
| 12 | 1″×17.02 | 109.0 | 98.14 | 16.2 | 20 | 47 | 14 | 17.7 |
| 13 | 1″1/4×3/4″ | 147.8 | 132.65 | 18.5 | 25 | 52 | 15 | 21.0 |
The highlighted row indicates the 15T sprocket detailed on this page. All sprockets in this range feature identical C45 steel construction and induction hardening treatment. Custom pitch sizes and tooth counts outside this standard range are available upon request with a minimum order quantity of 50 units per specification.
Key Features of Our Roller Chain Idler Sprocket
Induction-Hardened Contact Surfaces
Tooth flanks undergo precision induction heating followed by controlled quenching to achieve 45-52 HRC surface hardness. The hardened layer extends 1.2-1.8 mm from the tooth surface, providing wear resistance through approximately 3,000-5,000 operating hours under normal loading. The core material remains at 18-22 HRC, preserving the toughness required to absorb shock loads from equipment start-up and sudden load changes without crack initiation.
CNC-Hobbed Tooth Profile Accuracy
Teeth are cut using carbide-tipped hobs on CNC gear hobbing machines, producing tooth geometry within DIN 8196 Class 8 tolerances. Radial runout at the pitch circle diameter measures less than 0.15 mm. This precision reduces chain vibration amplitude by 12-18% compared to cast sprockets with non-machined tooth surfaces, contributing to quieter operation and measurable reductions in chain elongation rates over equivalent operating periods.
Controlled Bore Tolerances
Each bore is finish-reamed to H7 tolerance, providing a consistent slip-fit on standard shaft diameters. The hub face is machined perpendicular to the bore axis within 0.05 mm TIR, eliminating installation wobble that produces uneven tooth loading. For applications requiring a 3/4 inch bore roller chain idler sprocket or other custom bore dimensions, we offer machining to your specified shaft diameter with appropriate keyway sizing.
Bar Stock Material Traceability
Unlike cast sprockets that may contain internal porosity or inclusions, our replacement idler sprocket components are machined from C45 carbon steel bar stock with full material certification available. Each production batch is traceable to mill test reports documenting chemical composition and mechanical properties. This material consistency eliminates the risk of premature failure caused by casting defects that are undetectable through visual inspection alone.
Replacement Roller Chain Idler Sprocket for Industrial Equipment
When an idler sprocket reaches the end of its service life, the decision to replace it with an equivalent-quality component directly impacts remaining drivetrain longevity. Installing a substandard replacement accelerates wear on the chain, drive sprocket, and shaft bearings—components whose combined replacement cost typically exceeds the idler sprocket cost by a factor of 5 to 8 times.
Our roller chain idler sprockets are manufactured to function as direct replacements for original equipment components in ANSI 60 chain drive systems. Key dimensional specifications including pitch circle diameter (91.63 mm), tooth width (11.1 mm), and bore diameter (12 mm) are verified on every production batch using coordinate measuring equipment. This dimensional consistency ensures that installation requires no machine modification and that chain tracking alignment is maintained from the first operating cycle.
Replacement Indicators: Measure tooth thickness at the pitch circle using a sprocket wear gauge. Replace the idler sprocket when tooth thickness reduces by 8-10% from the nominal dimension. Visual indicators include hooked tooth profiles where the loaded flank develops a concave wear pattern, polished steps at the chain roller contact point, and measurable pitch variation exceeding 0.5 mm between adjacent teeth. Operating with a worn idler sprocket forces chain rollers to climb asymmetrical tooth profiles, accelerating new chain wear and increasing drive motor current draw by 5-8% due to increased friction.
Applications of Roller Chain Idler Sprocket
The 15-tooth configuration for 3/4-inch pitch chain serves across multiple industrial and agricultural sectors where ANSI 60 roller chain is the standard power transmission medium. This steel 15 tooth roller chain idler sprocket maintains chain tension and guides routing in the following application environments:
Agricultural Hay and Forage Equipment: Square baler knotter drives, round baler pickup reel chains, and forage harvester feed roll drives all employ 3/4-inch pitch chain with idler sprockets to maintain tension during fluctuating crop loads. The 15T configuration provides sufficient wrap angle to prevent chain jumping when wet crop material creates sudden resistance spikes. Operating environments expose sprockets to dust, plant sap residue, and intermittent moisture—conditions where induction-hardened teeth and corrosion-resistant surface treatment prevent accelerated wear.
Grain Handling Conveyors: Bucket elevators, drag conveyors, and belt conveyor head pulley drives in grain storage and processing facilities use ANSI 60 chain with idler sprockets positioned at tensioning stations. Chain elongation in conveyor applications typically reaches 2-3% before replacement, and properly maintained idler sprockets absorb this slack while preventing chain disengagement from drive sprockets during start-up torque surges.
Industrial Manufacturing Lines: Packaging machinery, textile looms, printing presses, and assembly line transfer systems incorporate idler sprockets to route chains around frame members and maintain tension across multiple shaft drives. These applications often accumulate 4,000-6,000 operating hours annually in multi-shift production schedules, making induction-hardened tooth surfaces essential for achieving acceptable replacement intervals.
Construction and Road Maintenance Equipment: Asphalt paver conveyor chains, concrete mixer drum drives, and road sweeper brush drives operate in abrasive conditions where mineral dust accelerates component wear. The hardened tooth surfaces on this replacement idler sprocket maintain profile integrity despite continuous exposure to fine aggregate particles that would rapidly abrade non-hardened alternatives.
Why Choose Our Industrial Chain Sprocket Solutions
Verified Tooth Hardness
Every production batch undergoes Rockwell hardness testing at multiple tooth positions. Test certificates are available with bulk orders, documenting compliance with the specified hardness range.
Bore Tolerance Standard
All bore diameters are finished to H7 tolerance and verified with plug gauges before release. This consistency eliminates installation fitting issues across multiple units in the same order.
Standard Lead Time
In-stock standard configurations ship within 7 working days. Custom bore sizes and keyway specifications typically complete within 15 working days from order confirmation.
Custom Order MOQ
Minimum order quantity for non-standard bore sizes, special materials, or custom tooth counts is 50 units. First-article samples provided for approval before batch production.
Frequently Asked Questions
How do I confirm this sprocket fits my chain size?
Measure three chain dimensions. First, measure the distance between the centers of three consecutive pins and divide by two—this gives chain pitch. This sprocket fits 3/4 inch (19.05 mm) pitch chain. Second, measure the width between inner link plates, which should be approximately 7/16 inch (11.1 mm) to match the tooth width specification. Third, count the thickness of the chain roller. If your measurements match ANSI 60 chain specifications, this roller chain idler sprocket will fit correctly. If you have the existing sprocket part number, provide it for direct cross-referencing.
Can I order this with a different bore diameter?
Yes. The standard configuration has a 12 mm bore, but we can machine 3/4 inch bore roller chain idler sprocket and other custom bore sizes from 10 mm to 25 mm to match your shaft diameter. Custom bore orders require a minimum quantity of 50 units per specification. Keyway dimensions are adjusted proportionally. Provide your shaft diameter and keyway requirements when requesting a quotation. First-article samples are available for verification before full production.
What surface treatment options are available?
Two standard options are offered. Black oxide provides a thin conversion coating suitable for indoor storage and dry operating environments. Zinc plating with clear or yellow chromate delivers 8-12 micron coating thickness with salt spray resistance exceeding 72 hours to white rust per ASTM B117. Zinc plating is recommended for equipment operating outdoors, in humid environments, or where occasional moisture exposure is expected. For food-grade or washdown applications, 304 stainless steel sprockets are available as a custom order option.
Should I replace the chain when replacing the idler sprocket?
Measure chain elongation before deciding. If chain elongation exceeds 2% (6.35 mm over a 12-inch/304.8 mm span of chain), replace the chain along with the idler sprocket. Installing a new sprocket against a worn chain transfers the chain's elongated pitch pattern to the new sprocket teeth, accelerating wear and reducing the new component's effective service life by 40-60%. If the chain
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| editor | wm |
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