Image

Troubleshooting Challenge: Hydraulic Motor Presents Problem on Coal Conveyor

July 2, 2014
A power plant has a conveyor that carries coal from a barge on the Ohio River to a storage pile. The beginning of the conveyor starts 10 ft below ground level and carries material up about 40 ft above the ground.
A power plant has a conveyor that carries coal from a barge on the Ohio River to a storage pile. The beginning of the conveyor starts 10 ft below ground level and carries material up about 40 ft above the ground.The conveyor is powered by an electric motor located in a pit, which was prone to flooding every time it rained. Maintenance workers decided to replace the electric-motor drive with hydraulics because a hydraulic motor would tolerate being under water occasionally.

The electric motor was rated at 15 hp at 1,800 rpm and supplied with 440 Vac, three phase, 60 Hz. Input speed to the conveyor’s gearbox was 1,800 rpm, so the electric motor used a belt drive with a 1:1 speed ratio. At full pressure, the hydraulic motor transmitted 18 hp at 900 rpm, so it used a 2:1 belt drive in order to provide the 1,800-rpm input speed to the conveyor. This gave a 20% safety factor for efficiency loss.

The conveyor ran well with the 15-hp electric motor, and the hydraulic motor was able to run the conveyor when it was empty. However, when the conveyor was loaded and stopped at the end of the work shift, the hydraulic motor could not start and run the conveyor.

All the math was checked and no error was found. So why was the electric motor able to power the conveyor, but the hydraulic motor wasn’t?

Find the solution

Think you know the answer? You can submit solutions by e-mailing [email protected].

All correct solutions will be entered for a chance at a $50 gift card — we will randomly select a winner from all correct submissions. The winner will be notified and his or her name will be printed in a future issue.

Congratulations to Paul Lopez, CFPS, of Michaelson Fluid Power Inc., Smithfield, R.I., whose name was drawn at random from those who correctly answered May’s “Troubleshooting Challenge.”

About the Author

Robert Sheaf | President

Robert J. Sheaf Jr., is the founder and president of CFC Insustrial Training, formerly Certified Fluid Consultants, part of CFC-Solar Inc. CFC-Solar provides technical training, consulting, and field services to any industry using fluid power technology. 

Continue Reading

Handbook Simplifies Advanced Aspects of Mobile Hydraulic Controls

May 10, 2017
Author Brendan Casey lays out his hydraulics know-how that he acquired over 27 years in a simple handbook made for people that want to improve their skills in troubleshooting ...

Kidney loops: They aren't just for hydraulics any more

Sept. 1, 2004
When was the last time you changed the oil in your refrigerator's compressor? That was a question posed to me by Ken Stofen of Racine, Wis. The answer, of course, is never, and...

Sponsored Recommendations

MONITORING RELAYS — TYPES AND APPLICATIONS

May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

All-In-One DC-UPS Power Solutions

March 13, 2024
Introducing the All-In-One DC-UPS, a versatile solution combining multiple functionalities in a single device. Serving as a power supply, battery charger, battery care module,...

Motor Disconnect Switches

March 13, 2024
With experienced Product Engineers and Customer Service personnel, Altech provides solutions to your most pressing application challenges. All with one thought in mind - to ensure...

DC Power Solutions: Streamlined Power Supplies for Every Need

March 13, 2024
CBI All In One UPS Power Solutions combine the requirements for several applications in just one device which can be used as power supply unit, battery charger, battery care module...