Robert Sheaf

Robert
J.
Sheaf
President,
CFC Industrial Training

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. 

Articles
Troubleshooting Challenge: Hoses Pull Away from Fittings
Technicians at a paper mill were puzzled by hydraulic hoses pulling loose from their end fittings.
Troubleshooting Challenge: HPU Is Too Noisy
Despite the manufacturer's tests to the contrary, hydraulic power units were shipped back because they tested above the 85-dBA noise threshold with the customer.
Troubleshooting Challenge: Cargo Ship Pressure Buildup Problem
What circuit issue caused a cargo ship's hydraulic power unit (HPU) to delay opening and closing hatch doors when pressing the solenoid button?
Troubleshooting Challenge: Mill Removal Circuit Doesn’t Move for Large Rolls
Technicians tried to solve why the cylinder of a temper mill's roll-removal system was struggling with heavier rolls.
Troubleshooting Challenge: Post-Hole Hammer Undergoes Pump Failures
The pressure-compensated pump in a hydraulic attachment for a front-end loader that hammered fence posts into the ground failed after only about two to three months of operation.
Troubleshooting Challenge: Cylinder Speed Running Slow
A progressive die press, designed to form shell casings for use in military tanks, started cycling slower after reassembly.
Troubleshooting Challenge: Accumulator Pre-Charge Changing
A mushroom farmer needed to solve the problem of their lift slowing down, and tried different methods to address possible issues with the HPU.
Troubleshooting Challenge: Compactor Return-Line Filter Problem
A large cardboard baler at a paper mill started blowing return filter elements off of the filter housing. The baler chamber would start off with little cardboard in it, then the large baler cylinder would extend until cardboard was compressed enough to cause hydraulic pressure to reach 4,500 psi. The piston rod would then retract based on pressure, not stroke position, for the next cycle.
Troubleshooting Challenge: Hydrostatic Side Thruster Stops Working
Despite flooding of the Ohio River this past spring, a large party riverboat was able to continue operating using its side thruster to facilitate docking, even though high forces from the rushing river occurred. But one day the thruster simply stopped working.
Troubleshooting Challenge: Lumberyard Stacker Cylinder Drops
A lumber company had an older yard stacker machine that they wanted to put back into service. The problem: The boom lift cylinder would drop when the operator also rotated the forks at the same time.
Troubleshooting Challenge: Elephant House Doors Open on Their Own
St. Louis Zoo officials asked Valtec Hydraulics Inc., St. Louis, to design a preventive maintenance program for hydraulic system in the zoo’s elephant house. A problem occurred after Valtec changed all five pressure filters during normal scheduled service.
Troubleshooting Challenge: Pump Keeps Losing Its Prime
Why wouldn’t the hydraulic pump hold its prime, and why did the flapper check blow out?
Troubleshooting Challenge: Pump-housing Cracking
A paper mill’s pump showed extensive piston barrel and shoes damage. But what caused it?
Troubleshooting Challenge: Speed Control Causing Unwanted Jolt and Pressure Spike 1
A casting plant used a simple two-speed circuit to extend a hydraulic cylinder at high speed, then shift to a slower speed for forming. The maintenance supervisor used the accompanying schematic to plumb the circuit.
Troubleshooting Challenge: Unexpected Pressure Loss while Testing A New Hydraulic Power Unit
In preparing for a retest of a hydraulic power unit experiencing quick pressure drops/rises, the oil was drained from the reservoir and panels removed, only to discover construction debris and beads of excess pipe dope at the bottom of the reservoir.
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