Legacy product now available for high performance couplings used in Petroleum, Chemical, Gas Industries as well as Power Generation applications


March 8th, 2021


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. When Compared to traditional hydraulic hubs, the Shrink Disc provides superior benefits that include an easier method of installation, resulting in a cost effective solution to the bottom the line.





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. This results in the elimination of galled shafts, and can replace traditional keyed and spline mounted hubs. Because the shrink disc allows the use of smaller diameter shafts to transmit the same amount of torque, users in the field will see experience an overall reduced overhung moment.



The Hydraulic Shrink Disc 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 shaft end connection, and we have seen a lot of successful implementation over the last decade in numerous different applications. 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.” Said Pat McCormack, Mechanical Engineer and Director of Business Development for Riverhawk Company.


Clamped Shaft End Connections is an emerging technology that has become more popular with end users as well as Original Equipment Manufacturers, due to the fact it has been solving issues commonly found among traditional shaft end connections. To learn more about Riverhawk Company or the Hydraulic Shrink Disc, please visit www.Riverhawk.com.


About Riverhawk Company

Riverhawk is a leading manufacturer and engineering design company with over 30 years of experience serving the petroleum and power generation industries. Their core product lines can be found among some of the most well-known companies who play pivotal roles in providing energy to the globe. Riverhawk products include application specific hydraulic tensioners, power train couplings, accessories, and instrumentation. In addition, Riverhawk offers a full suite of related services which such as maintenance, repair, and on-site training for turbomachinery and rotating equipment.

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