HTD-5M 80-120Teeth Timing Belt Pulleys Pitch 5mm AF-type With Keyway Width 21mm

The tooth count determines the pitch diameter and, combined with your motor pulley tooth count, sets your drive ratio. For a 1:1 ratio use matching tooth counts on both pulleys. For speed reduction, pair a smaller driver pulley with a larger driven pulley — for example, a 20T motor pulley with an 80T load pulley gives a 4:1 reduction. Calculate center distance and belt length after selecting your ratio.

Measure your shaft diameter with calipers and select the matching bore. Available bores are 10, 12, 14, 15, 19, 20, and 25mm. The bore must match the shaft exactly — an oversized bore will cause runout even with a keyway. If your shaft is imperial (e.g., 0.5 in / 12.7mm), choose the nearest metric bore and confirm the keyway fits your shaft key.

Keyway dimensions follow standard metric shaft key sizing: 10mm bore → 3×1.4mm; 12mm bore → 4×1.8mm; 15mm bore → 5×2.3mm; 19–20mm bore → 6×2.8mm; 25mm bore → 8×3.3mm. The 14mm bore uses a 5×2.3mm keyway. These match DIN 6885 / ISO 773 standard key dimensions for the respective shaft diameters.

These pulleys are compatible with any standard HTD-5M timing belt with a 21mm width and 5mm pitch, regardless of brand. The HTD tooth profile is an industry-standard geometry, so belts from Gates, Bando, or equivalent manufacturers will mesh correctly. Confirm your belt width is 21mm — narrower or wider belts will not track properly on this pulley.

Aluminum alloy pulleys are well-suited for most CNC, robotics, and automation drives operating at moderate torque levels. For very high-torque or shock-load applications (e.g., heavy industrial conveyors), consider whether a steel pulley is more appropriate. The AF-type keyway hub significantly increases torque capacity compared to set-screw-only designs by distributing load across the key rather than a single contact point.

Anodizing creates an aluminum oxide layer that resists oxidation and mild corrosion in typical indoor and light-industrial environments. For prolonged exposure to moisture, salt spray, or aggressive chemicals, additional protective measures (such as a sealant or enclosure) are recommended. The anodized finish also reduces surface wear from belt contact over time.

Yes, provided the replacement matches on all critical dimensions: tooth count, belt pitch (5M), belt width (21mm), bore diameter, and keyway size. Measure your existing pulley's pitch diameter or count the teeth, then select the matching variant. If the original pulley used a set screw without a keyway, verify your shaft has a keyway cut before installing this AF-type hub.