Riverhawk upgrades Hydraulic Shrink Disc

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Riverhawk Company, a provider of engineered tooling and solutions for turbomachinery and rotating equipment has announced that the Hydraulic Shrink Disc, an alternative design for shaft end connections that utilizes a clamping force on the hub, is now an acceptable alternative to traditional shaft end connections as defined in the newest release (5th edition) of the American Petroleum Institute standard 671(API STD 671).

The API STD 671 specifies the requirements for high performance couplings for the transmission of power between the rotating shafts of two machines in special purpose applications. These applications include petroleum, petrochemical, and natural gas industries.

The Hydraulic Shrink Disc is a legacy Riverhawk product that has been used as a replacement hub on shafts for other similar applications. Some of these include, but are not limited to, Generator, Pumps and Refrigeration applications. The Hydraulic Shrink Disc operates by using hydraulic pressure that activates a clamping force which squeezes the hub on the shaft, versus the typical dilation and pull-up designs.  It can also replace the keyed and spline mounted hubs. Another key advantage of the Hydraulic Shrink Disc is its ability to provide a reduced overhung moment by allowing the use of smaller diameter shafts to transmit the same amount of torque.


The Hydraulic Shrink Disc now meets requirements of the API STD 671 5th edition, as outlined in section 8.6.4, titled ‘Alternate Hub Design’. It states: “Alternative coupling-to-shaft juncture methods (providing an interference fit) other than keyed or hydraulically fitted hubs may be proposed as an alternative, as determined by the purchaser, provided such methods comply with all the requirements of this document, including but not limited to torque transmission and balance requirements. Any exceptions shall be approved by the purchaser.”

“The Hydraulic Shrink Disc has always been a viable alternative haft end connection, and we have seen a lot of successful implementation over the last decade in numerous different application," said Pat McCormack, Mechanical Engineer and Director of Business Development for Riverhawk Company. "The latest edition of API-671 is significant because now our clamped shaft end technology is available for those rotating equipment end users who work in the petroleum, petrochemical, and natural gas industries with high performance couplings."