EP-H300 12.700 mm Straight Bore Timing Pulley

The EP-H300 series covers 14 teeth (Dp 56.60 mm) through 156 teeth (Dp 630.64 mm) — one of the widest tooth count ranges available within a single H-pitch straight bore timing pulley catalogue series. This breadth enables a drive designer to cover speed reduction ratios from 1:1 through to approximately 11:1 with standard straight bore timing pulley catalogue parts, without the lead time and cost of custom machining. For global OEM machine builders specifying H-pitch straight bore timing pulley drives across multiple machine variants, this range availability from a single China timing pulley manufacturer eliminates the need for multiple vendor relationships across the size range.

The flange-to-flange dimension F is maintained at exactly 85.7 mm across the entire H300 straight bore timing pulley range, from the smallest 14-tooth steel pulley to the largest 156-tooth cast iron 6A construction. This dimensional uniformity means that all pulleys in the series accept the same standard H-pitch timing belt width and fit within the same axial envelope in the machine structure. Belt guides, tensioner brackets, and mounting hardware designed for one H300 straight bore timing pulley position are dimensionally compatible with every other position in the drive — a significant simplification for industrial machine design and aftermarket support programs.

The H pitch (12.700 mm) tooth is taller and wider than the L pitch (9.525 mm) tooth, generating a larger contact area per tooth at each mesh point. This results in significantly higher rated power per belt width compared to the L series at the same shaft speed, allowing the H300 straight bore timing pulley to drive loads that would require a wider or multi-strand L-series drive — at lower material cost and within a more compact drive envelope. For heavy industrial conveyor drives, large packaging line main drives, and high-torque servo axis applications in European and North American manufacturing, the H series straight bore timing pulley is the standard specification above the L series power boundary.

Steel (6F and 6WF types, 14–48 teeth) provides the straight bore timing pulley tooth root strength and bore wall integrity needed at the smaller compact pitch diameters. Cast iron (6W and 6A types, 49–156 teeth) provides straight bore timing pulley vibration damping and cost efficiency at larger diameters, where the mass of the rotating pulley also contributes useful flywheel inertia for smoothing cyclic torque loads. Both materials are machined to the tooth profile tolerances specified by ANSI MIL-T-23360, ensuring correct belt engagement and rated power capacity across the full straight bore timing pulley range of timing pulley standard sizes.

Unlike timing pulley series where the hub length varies with tooth count, the EP-H300 straight bore timing pulley maintains L = 100 mm for all 50 part numbers. This constant hub length ensures that the driven shaft engagement length, set screw position, and keyway depth are identical across all pulleys in the machine. Replacement pulleys, spare parts kits, and assembly procedures can be standardized across the full H300 straight bore timing pulley range — a direct reduction in engineering documentation effort and inventory management complexity for global maintenance programs covering multiple machine variants or multiple manufacturing plants.

Medium-carbon steel (S45C / C45 equivalent, SAE 1045 grade) provides the straight bore timing pulley tensile strength above 570 MPa in the normalized condition, rising to 750 MPa after surface hardening where specified. This strength level is required at the smaller pitch diameters (Dp 56.60 to 194.04 mm) where tooth root bending stress and the wall thickness available between the bore and the tooth root are both at their most demanding. The bore is precision-ground to the specified diameter, with surface finish Ra better than 1.6 μm for correct key fit. External surfaces receive zinc plating, black oxide, or enamel coating as standard for corrosion protection during storage and shipping.

Grey cast iron conforming to ASTM A48 Class 30 or ISO 185 Grade 200 is the standard material for H300 straight bore timing pulley products with 49 to 156 teeth (Dp 198.08 to 630.64 mm). At these larger diameters, cast iron provides vibration-damping properties that reduce the noise generation at H-pitch tooth mesh frequency, which — at the 12.700 mm pitch and the higher operating torques typical of H-series drives — can otherwise produce audible noise in enclosed machine structures. The 6A arm construction used for 58-tooth and larger straight bore timing pulley products reduces the casting weight at large diameters by replacing the full web disk with individual arms, maintaining structural rigidity while lowering the rotational inertia of the driven pulley assembly.

The straight bore timing pulley tooth profile is machined by CNC gear hobbing to the 40° included angle trapezoidal form specified for the H pitch by ANSI MIL-T-23360 and ISO 5294. The pitch, dedendum, and root radius values are controlled to the tolerance grades specified in the standard, ensuring correct belt seating and rated load capacity for the straight bore timing pulley at all operating speeds within the belt manufacturer rated speed range for H-pitch belts. Post-hobbing deburring removes sharp edges at tooth tips and flanks, and tooth profile accuracy is verified on CMM inspection equipment before dispatch.

The flanges on 6F and 6WF steel pulleys (14–48 teeth) are individual steel plate discs fixed to the pulley body, identified by the Flange Number column in the dimensional table (numbers 59 through 100 in the H300 range). Each flange plate provides the lateral retention that keeps the timing belt within the pulley rim width under the axial forces generated by belt tension variation and shaft misalignment. The Df column gives the flange outer diameter for each size. Cast iron 6W and 6A pulleys above 48 teeth do not carry separate flanges.

Large industrial belt conveyors in manufacturing plants, quarrying operations, and port facilities use H-pitch timing belt drives for their head drum and intermediate drive positions. The higher torque capacity of the H-pitch straight bore timing pulley compared to L-pitch alternatives allows wider conveyor widths and heavier belt loads to be driven with a single belt strand, eliminating the cost and complexity of multi-strand L-series drive configurations. The cast iron 6A straight bore timing pulley products in the 60 to 156 tooth range cover the large-diameter driven pulleys typical of conveyor head drives globally, including those supplying plant operators in North America, Australia, and Southeast Asia.

Web offset printing presses and digital wide-format printing systems use H-pitch straight bore timing pulley products in their main cylinder drive trains, where the positional accuracy of the synchronous belt drive directly determines registration quality. The timing belt idler pulley and tensioner arrangement in print machine drives maintains the belt at correct tension throughout the print cycle; each straight bore timing pulley in the print drive system contributes to overall registration accuracy; the EP-H300 pulley and matching H-pitch timing belt combination achieves the registration accuracy required for multi-color process printing. European print equipment manufacturers specifying H-pitch straight bore timing pulley drives for both domestic and export machine variants can source the complete H300 tooth count range from our China timing pulley facility.

Heavy case packing, palletizing, and strapping machines in the fast-moving consumer goods sector use H-pitch straight bore timing pulley products for their main transport conveyor drives and carton erection mechanism drives. At the higher machine throughput speeds — 30 to 60 cartons per minute — the timing belt drive must transmit significant tangential force at the belt pitch line without vibration that would affect carton placement accuracy. The EP-H300 range of steel 6F and 6WF straight bore timing pulley products in the 18 to 48 tooth range covers the compact drive positions typical of packaging machinery servo axes in global end-of-line automation equipment.

CNC turning centers, machining centers, and grinding machines use H-pitch straight bore timing pulley products for the main spindle drive where the motor and spindle are belt-coupled for vibration isolation and speed ratio flexibility. The H-pitch belt provides higher rated torque than the XL or L series at the same belt width, making it the standard choice for high-power spindle belt drives above 7.5 kW. The EP-H300 series steel straight bore timing pulley products in the 20 to 48 tooth range cover the compact motor-side and spindle-side pulley diameters used in machine tool main drive applications, with the constant 100 mm hub length ensuring consistent axial alignment across belt changes and replacement pulleys.

Combine harvesters, seeding machines, and crop processing equipment use H-pitch straight bore timing pulley drives for their threshing drum drives, straw chopper drives, and grain elevator mechanisms. The higher tooth load capacity of the H-pitch timing belt pulley straight bore timing pulley versus the L series makes it suitable for the shock loading and heavy debris-laden environments of agricultural machinery. The EP-H300 cast iron straight bore timing pulley products — with their inherent damping against shock impulse loads — are well suited to agricultural applications where belt tension variation from crop load spikes is a routine operating condition. Custom surface treatments including phosphatizing are available for H300 pulleys specified in outdoor agricultural equipment.

Weaving looms, carding machines, and nonwoven fabric production lines use H-pitch straight bore timing pulley products for the main shaft drives where the synchronous belt ensures precise angular velocity ratios between adjacent machine elements. In textile machinery, velocity fluctuation in the drive translates directly to fabric defects visible in the finished product — the zero-slip transmission of the H-pitch straight bore timing pulley and belt system eliminates this source of defects. The EP-H300 straight bore timing pulley range is sourced by textile equipment manufacturers across Turkey, India, Bangladesh, and Vietnam as a China timing pulley option meeting the timing pulley standard sizes required for their OEM specifications.

Metric pitch standard toothed bars are used where the H-pitch or metric timing belt drive produces linear motion output — positioning tables, linear axes on machine tools, and automated guided vehicle drives. When both the toothed bar and the driving straight bore timing pulley are sourced from the same supplier, the tooth profile geometry, pitch accuracy, and surface finish standards are consistent between the two components, ensuring correct mesh and rated linear force output. Toothed bars in T5, T10, AT5, AT10, and HTD metric pitches are available alongside our inch-pitch pulley range.

Many industrial machine drive trains use V-belt drives for the primary motor-to-gearbox stage and timing belt pulleys for the precision synchronous secondary stage. Our V-belt pulley range in classical A, B, C, D, and E sections and narrow SPZ, SPA, SPB, and SPC profiles complements the H-pitch straight bore timing pulley range, allowing a machine builder or maintenance workshop to source both drive types from one China timing pulley and power transmission supplier — simplifying procurement, reducing vendor qualification effort, and ensuring consistent material and coating standards across the complete drive train.