Archive for the ‘Fluid Drives’ Category


Geared Fluid Drives

December 15, 2016

Fluid drive applications that require an output speed that is faster than the input speed can utilize a gear set as a speed increaser.  Theoretically, a gear box can increase the speed  either before or after the fluid drive. However, it is usually better to increase the speed before the fluid drive because the size of the fluid drive parts are dependent on rotational speed at the hydraulic coupling: The faster the impeller, the smaller the parts.

TRI can make fluid drives with internal gears. A fluid drive with internal gears has two main advantages over a gear box external to the fluid drive. Machine trains that use fluid drives with internal gears have a smaller overall footprint then placing a gear box between the driver and the fluid drive, and fluid drives with internal gears eliminates the coupling between the drive and the fluid drive.

Call TRI for more information about fluid drives: (800) 363-8571


SIZE 195 Geared Fluid Drive
Input Speed = 1780, Output Speed = 5780



Fluid Drive Upgrades

May 14, 2014

Back in 2007, Dr. Mel created a presentation for fluid drive upgrades. This presentation explains how fluid drives are used specifically with boiler feed pumps. The operational history and the changes to the standard practices led to issues for which TRI has engineered solutions.






New Brake Installation

October 20, 2011

TRI has just completed the installation of a fluid drive brake. This system is similar to previous system that we have installed with the exception of larger calipers.

Industrial hydraulic brake for fluid drives

See our web site for more information about brakes and TRI Transmission and Bearing Corp.


Fluid Drive Brake Systems

November 22, 2010

The Purpose For The Brake System On A Fluid Drive

by Turbo Research Inc.

There is only one purpose for having a brake on the output shaft of a fluid drive; to aid in the operation of the boiler feed pump by stopping the boiler feed pump shaft and to keep it from rotating when the pump is out of service.

There are certain boiler feed pumps which are designed and built in ways that will cause them to gall and consequently to seize if they rotate for more than a few seconds or a few minutes at low speed with no or low flow through them. Typically, these pumps have stainless steel components that can rub together. They are often the higher performance, higher pressure pumps, but this is not always the case.

There usually is sufficient experience with each boiler feed pump over the years to know if that pump has or has not seized when it was at low speed during those times when a) the pump was out of service and simultaneously, b) the brake is imperative.

For those boiler feed pumps which have not seized when they were operated at low speed for several hours, or for which the manufacturer indicates that no problem will arise by operating at low speed with low/no flow, the brake is not required, and there is no value in using it.

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Sliding Pressure Operations

November 16, 2010

“Sliding Pressure” simply mans reducing boiler pressure in proportion to a reduction of MW generation. When “Power Wheeling” is fully effective, clearly those electrical generating units with the lowest cost will operate the most. Overall operating costs, efficiency, and/or “”eat rate”” as well as “turn down ratio” for each turbine-generator unit will be critical.

The “turn down ratio” is the ratio of maximum to minimum load. Those with high ratios are preferred because they can take a big swing from maximum load in the day to minimum load at night. Without coming off line.

“Sliding Pressure” for most sub-critical boilers is usually required to obtain the lowest minimum load a unit can achieve continuously and the maximum efficiency at that minimum load.

For fluid drive applications, a reduction of boiler pressure corresponds to a reduction of the output shaft speed/BFP shaft speed, resulting in increased heat, usually more than the amount for which the unit was designed, and often, high amplitude vibration.

TRI Transmission & Bearing Corp. has proven solutions in hand for fully evaluating and resolving these issues for all sizes and types of fluid drives, in BFP or other applications.

For certain units, during sliding pressure operation, new control valve opening patterns occur, leading to different “nozzle block” forces on the turbine rotors. TRI evaluates the changing rotor vibration conditions which result and makes recommendations, including the benefits provided by TRI Align-A-Pad ® bearings and other TRI products for reducing rotor vibration and bearing maintenance.


Fluid Drive Over Heating and Vibration Issues

October 12, 2010

Two common problems found in existing fluid drives (by other manufacturers of course) are over heating and vibration damage. TRI has a Tech Note that explains the history of fluid drives, the historic application for them in the US power industry and the problems that arose after power plants went moved away from providing base load power. Read more…


How TRI got into the fluid drive business

February 5, 2010

While documenting the IT system, I came across an article written in 1981. It explains how TRI improved the reliability of existing variable speed fluid drives.

Test, redesign, rebuild: Fluid-drive study concepts point way to upgrade equipment

Improvement of overall reliability demands scrutiny even of machinery that gives relatively little trouble. Learn how a program for large variable-speed boiler-feed-pump drives improved an already dependable element; even more important, how you can extend to your components the principles involved

By Dr. Melbourne F Giberson, P.E., Turbo Research Inc

The road to operating reliability in the central station is a difficult one, littered with breakdowns of equipment that went part of the way before a disappointing premature outage. The steam generator, the feed pump, the main turbine are a few of the major elements that have required searching and costly attention. Improvement in reliability is already clear for several categories of large machines, indicating that the goals are attainable.

For some of the humbler components, however, there has been scarcely a start toward constructive and cooperative work to widen the intervals between unforeseen outages. This work will have to be done if unit and station reliability and availability are to draw maximum benefit from the efforts on major elements. Perhaps new studies being planned can derive help from a series of programs covering shaft-driven fluid drives for boiler feed pumps.

These programs, for work done over a six-year period, resulted in modification recommendations to upgrade equipment that had by and large been satisfactory but was thought to be capable of some improvement. Keep; in mind that program details for other equipment will change. It is the program philosophy and the open cooperation among manufacturer, utility, and consultant that should be part of any new study of reliability enhancement.

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