Hydraulic Pump Gear Set

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Hydraulic Pump Gears
Hydraulic Pump Gears

A sector of gear manufacturing that requires very high strength and precision is hydraulic gear pumps. Gear pumps comprise the most common type of pump; this is due to their simplicity and ability to be engineered to accommodate a wide range of pressures and RPMs. In this project, the requirements for high pressure and high RPMs, combined with very tight tolerances and difficult to machine materials (H13 tool steel), made this a very challenging project. Success with projects like this require teamwork; our senior engineers, gear shop supervisor, senior grind room operator, and our entire quality assurance team all play a major role in the manufacturing of these types of pump gear sets.

A critical factor to gear sets for pumps is that they must be manufactured as a matched set; this requires much greater precision and can be a real challenge for quality assurance. Fortunately, at American Precision Gear, we have of 40 years of experience manufacturing tight tolerance high strength pump gears sets. We are also ISO certified, with a robust quality program; as a result, we now produce these gear sets in orders of 50 sets, four times per year.

This gear set is designed with 8 teeth, 7DP, and a 28° pressure angle, with an involute flat root, side fit spline with 13 teeth, 32/64 DP, a 30° pressure angle, and required to have a finish of no greater than 63 RMS. All tolerances were in line with AGMA 12 gear tolerance standards, and included .0005" TIR or FIM on the 0.6200" bore I.D. and the 1.4285" O.D. and 1.4820"/1.4805" MOW.

Machining this product required many machining and finishing processes, and as the dimensions indicate, a comprehensive set of quality checks. The fully traceable H13 tool steel that was used was subject to CNC turning, broaching, grinding, and gear grinding (hobbing). Our shop is equipped with a large number of state of the art machining systems, most of which are CNC equipped. This advantage allows for higher throughput, faster setup, and enhanced quality. Additional processes included deburring, side wheel grinding/lapping, heat treating and nitriding. Dimensions and quality were verified with the use of a visual comparator and CMM, and finally nondestructive testing in the form of magnetic partial inspection. This level of verification is all in compliance with AGMA quality testing and verified with CoCs for each gear set.

To learn more about this project, see the table below or contact us directly.

Hydraulic Pump Gear Details

Overall Part Dimensions
8 Teeth, 7 DP, 28° Pressure Angle &
13 Teeth 32/64 DP 30° PA Internal Involute Flat Root, Side Fit Spline
OD: Ø 1.442 / 1.440
Length: 4.625"
Tightest Tolerances
0.6200 Bore ID, 1.4285 OD to .0005 TIR or FIM
1.4820/1.4805 MOW, AGMA 12 Tolerances
Material Used
H13 Tool steel
Material Finish
63 RMS Max