A monster machine that bends 10″ pipe
This machine is being built to bend 10″ round pipe. Tim “the tool guy” Allen from Home Improvement would be proud of this bad boy.
This is a production jig we are building for a client to use to make the parts easier to grab and use during production. (the springs on the parts get tangled up if they are just put into a pile) We built more than 50 of the these jigs for them so far.
If you need any jigs or fixtures similar to this one give us a call.
Craig Cook
Okay so it isn’t exactly a beast BUT it is a huge bench that allows us to test every aspect of any hydraulic component.
When you have us repair or rebuild any hydraulic component, it goes through rigorous testing on our hydraulic test stand.
We use the test stand for:
Every repair goes through testing on this bench to make sure it meets and exceeds the needs your requirements.
If you need anything repaired feel free to give us a call at (260) 426-4673.
Till next time,
Craig Cook
Tapered thread connections can have a tendency to leak. If you have to use tapered thread connections, there are tricks to minimize them from leaking.
How to minimize the chance of your tapered thread connections from leaking.
First, don’t waste your time with thread tape – I only ever use it when there’s no thread sealing compound available. I’ve had best success with Loctite 567 and 577 (my favorite), which are pastes rather than liquids like some of the others.
If you’re re-sealing a joint, thorough cleaning of the old adaptor and port is essential. If you’re in your workshop, a brush wheel in a bench grinder does a great job on the threads of the adaptor. But the female threads in the port aren’t so easy.
Once you’ve removed all remnants of thread tape or sealant, the next step is to use the appropriate Loctite cleaner. Don’t skip this step – you’ll regret it.
Next, if you’re not able to wait the 6 hours or so for acceptable cure strength, apply the Activator 7649 and allow it to dry. If you have the luxury of leaving the joint overnight
before pressurizing it, you can skip this step.
Starting two threads back, apply a bead of paste around the entire circumference – completely filling the threads. Do the same with the female threads in the port.
Now torque the joint. I will go over proper torquing next week.
Craig Cook
The BEST time to carry out a maintenance and reliability audit on a piece of hydraulic equipment is BEFORE you buy it.
By starting with the end in mind, you get the reliability outcomes you desire – before the machine even gets delivered.
For example:
You specify the contamination control targets you want to achieve based on your reliability objectives for the piece of equipment.
And instruct the manufacturer to deliver the machine appropriately equipped to achieve these targets.
Based on the weight and viscosity index of the hydraulic oil you plan to use, you determine the minimum viscosity and therefore the maximum temperature you want the machine to run at.
And instruct the manufacturer to deliver the machine equipped with the necessary cooling capacity, based on ambient temperatures at your location. Rather than accepting hydraulic system operating temperatures dictated by the machine’s ‘design’ cooling capacity – as is the norm.
And we could continue by specifying things like flooded inlet for all pumps and so on. But you get the idea.
So the next time you or the company you work for are looking to acquire hydraulic equipment, begin with the end in mind.
Define your maintenance and reliability objectives in advance and make them an integral part of your equipment selection process. Craig Cook
Here’s the final part of our 3 part series on hydraulic trouble shooting 101.
STEP 5 – Relief Valve…
If the test in STEP 3 has indicated the trouble to be in the relief valve, point D, the quickest remedy is to replace the valve with one known to be good. The faulty valve may later be disassembled for inspection and cleaning.
Pilot-operated relief valves have small orifices which may be blocked with accumulations of dirt. Blow out all passages with an air hose and run a small wire through orifices.
Check also for free movement of the spool. In a relief valve with pipe thread connections in the body, the spool may bind if pipe fittings are over-tightened. If possible, test the spool for bind before unscrewing threaded connections from the body, or screw in fittings tightly during inspection of the valve.
STEP 6 – Cylinder…
If the pump will deliver full pressure when operating across the relief valve in STEP 2, both pump and relief valve can be considered good, and the trouble is further downstream. The cylinder should be tested first for worn-out or defective packing by the method described in our guide “Cylinder and Valve Testing”. Other Components…
Check other components such as bypass flow controls, hydraulic motors, etc. Solenoid 4-way valves of the pilot-operated type with tandem or open center spools may not have sufficient pilot pressure to shift the spool.
If you still have problems…
If you still have questions or problems after trying to troubleshoot your hydraulic system, feel free to give us a call and have one of our hydraulic specialists come and give you a hand.
Craig Cook
Here’s part 2 of our 3 part series on hydraulic trouble shooting 101.
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STEP 3 – Pump or Relief Valve…
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If high pressure cannot be obtained in STEP 2 by running the pump against the relief valve, further testing must be conducted to see whether the fault lies in the pump or in the relief valve. Proceed as follows: If possible, disconnect the reservoir return line from the relief valve at point H. Attach a short length of hose to the relief valve outlet. Hold the open end of this hose over the reservoir filler opening so the rate of oil flow can be observed. Start the pump and run the relief valve adjustment up and down while observing the flow through the hose.
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If the pump is bad, there will probably be a full stream of oil when the relief adjustment is backed off, but this flow will diminish or stop as the adjustment is increased. If a flowmeter is available, the flow can be measured and compared with the pump catalog rating. If a flowmeter is not available, the rate of flow on small pumps can be measured by discharging the hose into a bucket while timing with a watch.
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For example if a volume of 10 gallons is collected in 15 seconds, the pumping rate is 40 GPM, etc. If the gauge pressure does not rise above a low value, say 100 PSI, and if the volume of flow does not substantially decrease as teh relief valve adjustment is tightened, the relief valve is probably at fault and should be cleaned or replaced as instructed in STEP 5.
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If the oil substantially decreases as the relief valve adjustment is tightened, and if only a low or moderate pressure can be developed, this indicates trouble in the pump. Proceed to STEP 4.
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STEP 4 – Pump…
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If a full stream of oil is not obtained in STEP 3, or if the stream diminishes as the relief valve adjustment is tightened, the pump is probably at fault. Assuming that the suction strainer has already been cleaned and the inlet plumbing has been examined for air leaks, as in STEP 1, the oil is slipping across the pumping elements inside the pump. This can mean a worn-out pump, or too high an oil temperature.
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High slippage in the pump will cause the pump to run considerably hotter than the oil reservoir temperature. In normal operation, with a good pump, the pump case will probably run about 20F above the reservoir temperature.
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If greater than this, excess slippage, caused by wear, may be the cause. check also for slipping belts, sheared shaft pin or key, broken shaft, broken coupling, or loosened set screw.
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Many of the failures in a hydraulic system show similar symptoms: a gradual or sudden loss of high pressure, resulting in loss of power or speed in the cylinders. In fact, the cylinders may stall under light loads or may not move at all. Often the loss of power is accompanied by an increase in pump noise, especially as the pump tries to build up pressure.
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Any major component (pump, relief valve, directional valve, or cylinder) could be at fault. In a sophisticated system, other components could also be at fault, but this would require the services of an experienced technician.
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By following an organized step-by-step testing procedure in the order given here, the problem can be traced to a general area, and then if necessary, each component in that area can be tested or replaced.
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STEP 1 – Pump Suction Strainer
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Probably the trouble encountered most often is cavitation of the hydraulic pump inlet caused by restriction due to a dirt build-up on the suction strainer. This can happen on a new as well as an older system. It produces the symptoms described above: increased pump noise, loss of high pressure and/or speed. If the strainer is not located in the pump suction line it will be found immersed below the oil level in the reservoir (point A).
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Some operators of hydraulic equipment never give the equipment any attention or maintenance until it fails. Under these conditions, sooner or later, the suction strainer will probably become sufficiently restricted to cause a breakdown of the whole system and damage to the pump. The suction strainer should be removed for inspection and should be cleaned before re-installation. Wire mesh strainers can best be cleaned with an air hose, blowing from inside out. They can slso be washed in a solvent which is compatible with the reservoir fluid. Kerosene may be used for strainers operating in petroleum base hydraulic oil. Do not use gasoline or other explosive or flammable solvents.
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The strainer should be cleaned even though it may not appear to be dirty. Some clogging materials cannot be seen except by close inspection. If there are holes in the mesh or if there is mechanical damage, the strainer should be replaced. When reinstalling the strainer, inspect all joints for possible air leaks, particularly at union joints (points B, E, G, H, J, and K). There must be no air leaks in the suction line.
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Check the reservoir oil level to be sure it covers the top of the strainer by at least 3″ at minimum oil level, with all cylinders extended. If it does not cover to this depth there is danger of a vortex forming which may allow air to enter the system when the pump is running.
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STEP 2 – Pump and Relief Valve
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If cleaning the pump suction strainer does not correct the trouble, isolate the pump and relief valve from the rest of the circuit by disconnecting at point E so that only the pump, relief valve, and pressure gauge remain in the pump circuit. Cap or plug both ends of the plumbing which was disconnected. The pump is now deadheaded into the relief valve.
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Providing control reliability with fluid power is not quite the same as with electrical controls, however. For instance, plain redundancy in a safety circuit requires the equivalent function of four valve elements, not just two. Two of the four valve elements handle the inlet function while the other two elements handle the stop function (energy release). Many self-designed systems risk having hidden, potential flaws, which can lead to unsafe conditions because they are unseen, unexpected and, therefore, excluded from design and safety reviews. A good example is the spool cross-over conditions or ghost positions of a valve, which are usually not shown on schematics. a
Two general abnormal conditions can affect valve safety. The first is similar to an electrical-control fault, such as when a relay might be stuck in the open or closed position. The second is when a valve develops diminished performance, as when a valve becomes sticky or sluggish. In such cases, the valve reaches the proper position, but slower shifting affects safe stopping distances or precise timing. The ANSI B11.19-2010 Standard mandates a monitoring system that detects these conditions for critical applications and the ANSI/PMMI B155.1-2011Standard requires diminished performance monitoring if stopping time can be affected. An easy solution is to use a self-monitoring, Category-3 or -4 valve, designed to detect both conditions. a
The use of double valves remained relatively unheard of for many years except in a few select industries, such as stamping presses, which first initiated control reliability requirements. Double valves provide dual internal functions (redundancy) so that an abnormal function of one side of the valve does not interfere with the overall normal operation. At the same time, the double valves sense abnormal operation on either side of the valve and then inhibit further operation until the problem has been corrected and the valve deliberately reset. This sensing and inhibiting function is commonly referred to as monitoring. a
Two standard air valves, whether in parallel or in series, cannot perform the same safeguarding function as does a double valve critical function. By simply incorporating two standard air valves into the circuit, no provision is made to sense the abnormal operation of one side of the valve or, even more preferable, diminished performance such as slow shifting. In addition, there is no provision for inhibiting further operation of the circuit until the valve is repaired. If one valve actuates abnormally, the second one continues to function and redundancy is lost. The circuit doesn’t recognize lost redundancy nor would it halt operations as a warning that redundancy has been compromised. Then, if the second valve also actuates abnormally, there is no back up and control integrity no longer exists. a
Double valves are appropriate for pneumatic and hydraulic equipment anytime reliability is an issue. Typical applications include E-stop, two-hand-control, light curtains, safety gates, pneumatic locking devices for safety gates, hydraulic brakes, air brakes, amusement rides, hoists, elevators, pinch-point applications, or any other application where control system integrity depends on valve operation. a
Craig Cook
Air typically enters the hydraulic system through the the pump inlet and, under certain conditions, past the rod seal of a double-acting cylinder.
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But air can also invade the system through joints in pressurized plumbing.
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When fluid travels through a pipe or hose at relatively high velocity – in a pressure line for example, and has to change direction through a tee or elbow, a venturi effect can be created.
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Because the sealing arrangement of the hydraulic connector is designed to withstand positive pressure – but not negative pressure, air can be drawn into the system – even when the plumbing has no apparent leaks.
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If you made a glass model of a pipe elbow and connected a measuring point in the middle of the angle, you would see a negative pressure when fluid passed through the elbow at high velocity.
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And if you looked carefully, you’d likely see air bubbles entering the system through the seal of the measuring connection.
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What it comes down to is use as few sharp angles – tee-pieces, elbows, etc in hydraulic plumbing as possible. a
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Craig Cook
