Endurance Test Stand

Posted on Tuesday, February 2, 2016 in UEA Blog

United Equipment Accessories has been working on a test stand to run an accelerated live test on hydraulic swivels.  Listed below are some of the key points this test stand offers.

The overall footprint of this machine is 86” wide x 53” deep x 103” high. It contains the test stand which is 48” wide x 48” deep x 96” high; the test chamber itself is 28” x 28” x 42”. The front door can only be opened after the machine is shut down. A linear solenoid, which latches the door, can only be energized when the machine is shut down to open the door. Only when the front door is closed and detected by a proximity sensor can the machine be started.  The top doors are manually opened to help with the installation and removal of the swivels. The test chamber is enclosed using polycarbonate sheet and expanded flattened sheet metal on all sides.

A 25 gallon reservoir contains a liquid level and temperature switch. The oil cleanliness specification is ISO4406: 17/15/12 and is measured by an inline contamination monitor. An oil cooler is located above the reservoir. The return oil is cleaned by a 3 micron filter. There are three electric motor-hydraulic pump units which supply oil for low/medium pressure circuits, the high pressure circuits, and the hydraulic motor. There are also two pressure oil filters to keep the oil clean and protect the proportional valves.

The swivel is rotated by a hydraulic motor that has the capability to produce up to 1500 ft-lb of intermittent torque.  The hydraulic motor and a torque arm are assembled to a turntable which allows for degrees of freedom.  The torque is measured by a 2000 lb capacity load cell connected between the torque arm and ground. The swivel rests on a drive plate which has two drive pins that rotates the spool in both clockwise and counter-clockwise direction and is controlled by a solenoid valve. The maximum rotational speed of the swivel may be up to 10 rpm. The rotational speed is measured by a proximity switch. The Housing is constrained back to the main frame with height adjustment square tubes. These are positioned for each individual swivel using acme screws and gearboxes. The frame is gusseted to handle the forces produced during the rotation of the swivel.

Hydraulic pressure testing of the swivel flow grooves will have three different pressure ranges. These pressures are preset using proportional valves. The pressures will alternate during a specified testing criteria to simulate the actual function of the swivel. There are (4) 4 station dual solenoid valves that route the oil to the correct flow groove. One is for the high pressures and another for medium pressures, the other two can be used for either high, medium or low pressure circuits. There are also four O on/off solenoid valves for diverting medium pressures if a flow groove is subjected to more than one pressure. This is all determined by the test parameters of the swivel.

A data acquisition system will measure and record torque and pressures during testing. Periodically we’ll do a pressure decay on each flow groove. We’ll also monitor oil cleanliness and record the temperature at our high pressure cap seals using thermocouples.

A cold start up test may be required and is done at -40 degrees Fahrenheit. This is accomplished by either cold soaking the swivel with liquid nitrogen or packing it with dry ice. This temperature needs to be held for one hour. The swivel may also need to be tested at 220 degrees Fahrenheit using heat blankets or heating cartridges. The temperature variations will be measured using thermocouples.

This test stand will be located in an enclosed room that has a two hour fire rating and fire suppression system. There is a 8′ x 12′ roll-up overhead door and two walk-through side doors, one on each side. The overall size of the room is 23′-4″ W x 20′ D x 15′ H with a ceiling clearance of 12′. There will also be ventilation to remove any heat built up after testing. This ventilation can also be shut down automatically if needed. The room provides the means to run a test 24/7, and it can be monitored from our desks. The room is large enough to hold another test stand in the future to run two tests simultaneously.

Thomas Van Veldhuizen