EP-H75 12.7mm スチール＆鋳鉄製ストレートボアタイミングプーリー

H Series — Heavy Duty Straight Bore Timing Pulley

EP-H75 12.7MM Steel & Cast Iron Straight Bore Timing Pulley

A heavy-duty straight bore timing pulley in the H 075 series, featuring a 12.700 mm pitch — the standard for medium-to-high torque industrial synchronous belt drive applications. Available in 27 tooth counts from 14T to 50T in Steel (6F type, 14T-42T) and Cast Iron (6WF and 6W type, 44T-50T) materials. Designed for conveyor drives, machine tools, packaging lines, textile machinery, and industrial automation systems requiring robust straight bore timing pulley construction worldwide.

ストレートボアタイミングプーリー

Key Technical Facts

2. What Is the H 075 Straight Bore Timing Pulley?

The H 075 straight bore timing pulley is the standard-pitch heavy-duty category of synchronous belt drive pulleys, using the H (Heavy) series 12.700 mm pitch designation that is part of the ANSI/RMA trapezoidal tooth timing belt standard. The 12.700 mm pitch — exactly half an inch — is a legacy of the American industrial standards from which the modern timing belt pulley series evolved, and it remains the dominant pitch in the medium-torque industrial machinery segment worldwide. The straight bore timing pulley design centralises the bore on the pulley rotation axis with a parallel keyway for shaft-key torque transmission, the simplest and most direct mounting approach for pulleys where removal for belt replacement or drive ratio adjustment is a regular maintenance task.

In the H 075 series, the 075 designation refers to the belt width in hundredths of an inch — 0.75 inches or 19.05 mm — indicating that this straight bore timing pulley series is designed for use with H-pitch timing belts of 0.75-inch face width. The actual machined face width F of the H 075 straight bore timing pulley is 26.4 mm across all 27 tooth count variants, which provides the necessary belt face support plus the flange clearance width beyond the belt edges. The consistent F = 26.4 mm across all sizes ensures that the same H-pitch timing belt width can be used with any tooth count variant in the series without changing the belt width specification, significantly simplifying procurement and inventory management for industrial maintenance teams sourcing timing belt pulley replacement parts for mixed-ratio conveyor and machine tool drive systems.

The material transition from steel to cast iron at 44T reflects the production economics and mechanical requirements of different pulley size ranges. Below 44T, the steel H 075 straight bore timing pulley units are machined from solid steel bar or precision blanks on CNC turning and hobbing equipment, producing precise tooth geometry and hub bore concentricity. Above 44T, the larger diameters (Dp from approximately 178 mm upward) are more economically produced as cast iron blanks with a rough cast tooth form subsequently machined to final profile, combining the material density and vibration damping of cast iron with the machining accuracy required for acceptable timing belt pulley tooth mesh quality. Understanding these material and structural differences helps OEM machine builders and industrial procurement engineers select the correct H 075 straight bore timing pulley specification for each drive circuit in their machinery.

3. Five Key Product Advantages

4. H 075 Series — Complete Dimensional Specifications

Pitch: 12.700 mm (H series). All dimensions in mm. Dp = pitch circle dia.; De = outside dia.; Df = flange dia.; Dm = hub dia.; Di = bore (customer-specified); F = face width; L = hub length; d = key width; Flange No. = mating flange reference. Type 6F = six-bolt steel flange; 6WF = welded cast iron flange; 6W = integral cast iron web.

Di (—) = bore to customer specification. Df (—) for 6W types = no bolt-on flange. Key width d = 8 mm (14T-17T), 11 mm (18T-42T), 14 mm (44T-50T). All dimensions in mm.

4a. Straight Bore Timing Pulley Selection Guide — H 075 Series

Selecting the correct H 075 straight bore timing pulley for a new or replacement drive application requires confirming four parameters before placing an order: tooth count for the required speed ratio, material based on load and diameter, bore diameter matching the shaft, and flange type based on the machine installation. Engineers who need to replace an existing straight bore timing pulley without the original part number should work from the five physical measurements described in FAQ Q4 — the measured pitch circle diameter, bore, keyway width, hub length, and flange type together uniquely identify the correct H 075 straight bore timing pulley specification from the dimension table.

For drive ratio selection: the speed ratio equals the driven straight bore timing pulley tooth count divided by the driving straight bore timing pulley tooth count. A 22-tooth driver paired with a 44-tooth driven straight bore timing pulley produces exactly 2:1 speed reduction. The choice of specific tooth counts within a given ratio should also account for centre distance constraints — the pitch diameter of each straight bore timing pulley (from the Dp column in the table) determines the minimum centre distance for adequate belt wrap angle at both pulleys. Most industrial drive designers target a minimum wrap angle of 120 degrees at the smaller straight bore timing pulley to ensure multi-tooth engagement at all load conditions.

Bore specification for the H 075 straight bore timing pulley should match the shaft diameter to H7/h6 clearance fit for standard keyway-retained drives. For timing pulley stock distributors, the most efficient approach is to hold the pre-machined blank at a standard bore size and finish the bore on arrival at the machine shop — this is exactly what the straight bore timing pulley is designed for, and it gives distributors and MRO procurement teams maximum flexibility from a single timing pulley stock item. As a specialist timing pulley manufacturer, we can also supply H 075 straight bore timing pulley units with a completed finished bore to your specification, including the keyway and setscrew, ready for direct installation — useful for maintenance teams who need timing belt pulley replacement units that are immediately field-ready without machine shop work. Contact our technical sales team with the shaft diameter and key specification for a quotation on finished-bore straight bore timing pulley supply.

5. Working Principle of the H 075 Straight Bore Timing Pulley

The H 075 straight bore timing pulley transmits rotational power from a drive shaft to an H-pitch timing belt through tooth-to-groove positive engagement. The motor shaft passes through the straight bore, with the parallel key seating in matching keyways in both the shaft and the straight bore timing pulley hub, transmitting the drive torque from shaft to pulley by shear stress in the key body. The set-screw (at the hub outer diameter) prevents the straight bore timing pulley from sliding axially on the shaft without providing the primary torque transmission that the key handles. This combination of key torque transmission plus set-screw axial retention is the standard straight bore timing pulley configuration for industrial synchronous belt drives up to the moderate torque levels for which the H 075 series is designed.

As the straight bore timing pulley rotates, H-pitch timing belt teeth engage with the pulley tooth grooves sequentially. Each belt tooth entering a groove displaces the previous tooth out of its groove on the departing side, creating the synchronous belt meshing action that transmits the drive force without slip. The 12.700 mm pitch defines the center-to-center spacing of adjacent teeth, giving a belt tooth pitch circumference per revolution equal to the tooth count multiplied by 12.700 mm — a 24 H 075 straight bore timing pulley has a pitch circumference of 24 × 12.700 = 304.8 mm, equivalent to the 97.02 mm pitch circle diameter in the dimension table. The flange plate (6F type on steel pulleys) prevents the belt from tracking laterally off the straight bore timing pulley under misalignment forces or transverse loading, maintaining belt engagement across the full 26.4 mm face width throughout the drive operation.

The cast iron pulleys at 44T and above (types 6WF and 6W) introduce a design change at the hub transition from steel to cast iron: the 6WF type retains a bolt-on flange (Df specified, separate flange ring bolted to the pulley body), while the 6W type at 49T and 50T uses an integral web and hub with no separate flange (Df shown as —), relying on the larger Dm hub diameter and deeper bore engagement to provide the shaft mounting stability that the flange contributes in smaller straight bore timing pulley units. The larger Di bore available at these sizes (up to 90 mm hub body diameter Dm = 170-174 mm) accommodates larger industrial drive shafts that carry the higher torques associated with the large pitch diameter of 49T and 50T H 075 straight bore timing pulley units at rated H-pitch belt tension.

6. Materials and Construction

The material selection for each tooth count range in the H 075 straight bore timing pulley series reflects both the structural requirements and the manufacturing process economics for the pulley diameters involved.

7. アプリケーションシナリオ

The H 075 series straight bore timing pulley is designed for the following primary industrial and commercial applications where the 12.700 mm pitch H-series synchronous belt drive is the correct specification.

8. Regulatory and Standards Framework

H 075 straight bore timing pulley units are manufactured and traded in a regulatory context that covers product dimensional standards, machinery safety requirements, and material compliance in the major global markets.

ANSI/RMA IP-24 and IP-26 — Trapezoidal Tooth Timing Belts and Pulleys: These Rubber Manufacturers Association standards define the H series 12.700 mm pitch tooth profile, groove geometry, and dimensional tolerances for timing pulleys. All dimensional data in the H 075 specification table conform to ANSI/RMA IP-26 H series straight bore timing pulley dimensions, ensuring interchangeability with H pitch pulleys from any supplier producing to the same standard. This interchangeability is the basis for global timing belt pulley replacement procurement and OEM machine servicing across North American, European, and Asian markets where ANSI/RMA standards are recognized as the applicable technical standard for this straight bore timing pulley product category.

ISO 22458 — Synchronous Belt Drives: The ISO standard for synchronous belt drives covers the dimensional requirements for timing pulleys and belts across the trapezoidal tooth pitch series including H pitch. ISO 22458 alignment with ANSI/RMA IP-24 provides the international standards basis for procurement specifications in ISO-regulated markets including the EU, UK, Japan, and South Korea where EN-referenced ISO standards are required for industrial machinery component procurement documentation. The timing belts and pulley system governed by ISO 22458 allows buyers across different global markets to specify the H 075 straight bore timing pulley with confidence in cross-manufacturer dimensional compatibility.

EU Machinery Directive 2006/42/EC — Power Transmission Guards: Timing belt and pulley drives incorporated in machinery sold in the EU must comply with the Machinery Directive Annex I Section 1.3.1 requirement for guarding of power transmission components. The H 075 straight bore timing pulley drive assembly (pulleys plus belt) constitutes an exposed rotating element that must be enclosed by a fixed or movable guard in the completed machine. Machine builders incorporating H 075 straight bore timing pulley units into EU-market equipment should ensure the drive guard design is included in the Machinery Directive technical file and CE declaration for the completed machine.

RoHS Compliance: The steel and cast iron materials used in the H 075 straight bore timing pulley series contain no restricted substances under EU RoHS Directive 2011/65/EU or equivalent legislation in the UK, Taiwan, South Korea, and Japan. RoHS compliance declarations are available on request for customers assembling electrical and electronic equipment subject to RoHS requirements that incorporate this straight bore timing pulley series in their drive systems.

9. About Us

We are a professional timing pulley manufacturer and global exporter producing the full range of standard synchronous belt drive pulleys including the H 075 straight bore timing pulley: MXL, XL, L, H, XH, and HTD (3M, 5M, 8M, 14M) series in aluminum, steel, cast iron, and stainless steel, in straight bore and taper bore configurations from stock and to custom specification. Our production facility operates CNC gear hobbing, profile milling, turning, and boring centers with in-process dimensional inspection to ANSI/RMA and ISO standards. As a dedicated timing pulley manufacturer with global supply capability, we provide timing pulley stock from standard ranges and custom straight bore timing pulley production on verified lead times for OEM and MRO customers worldwide.

ワークショップ

10. Compatible Products

The H 075 straight bore timing pulley is the core of a complete H-pitch synchronous belt drive system. We supply compatible components for full drive system procurement from one source.

よくある質問