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Test Report for automobile lifting device. The purpose of the test is to pass ANSI B153.1, a standard for automotive lifts - Safety requirements for the construction, care, and use. Testing conducted
at Cytech Test Parameters: Return to Top The engineers at MAMTC were asked to look at testing a model DP-6 automobile lift for Cytech. The end result of the testing is certify to ANSI 153.1 standard for auto lifts. The model DP-6 auto lift is a four post lift intended for use as an auto storage mechanism. It was the desire of the management at Cytech to pass the ANSI 153.1 criteria even though the lift is not primarily used in a service environment. The specification lists several parameters to be considered in this test. These are:
The test article was placed under load and the following was observed:
The test was designed to load the auto lift with a static load equal to the strength factor described in the specification. For this lift, this strength factor was 3, based on the rated load capacity. At the time of the test, the DP-6 was rated at 6000#. It was also desirable to see if the lift would withstand a rating of 7000# to change model to a DP-7. The main criteria for this segment of the test was paragraphs 4.1.11, and 4.1.14. These paragraphs involved the strength factor for the superstructure and the locking mechanism. The test setup is shown in figure 1. The hydraulic cylinder used has a 4 inch diameter bore with a 1.25 inch diameter piston road. The hydraulic pressure on the cylinder was monitored and translated to force the test article. The loss due to the cylinder were taken into account when the pressures were correlated to force. The test fixture on top of the runways which were spaced at 110 inches to simulate a vehicle sitting on the lift weighed 1239 pounds which was subtracted from the force applied by the cylinder for the total load. The test articles were placed under load and taken to a level equivalent to 18,000 pounds. This load represented a strength factor of 3 for a rated capacity of 6000 pounds. The superstructure and locking devices held with no signs of failure. The load was then increased to the equivalent of 21,000 pounds which represented a strength factor of 3 for a rated capacity of 7000 pounds. This result allows Cytech to reclassify the model DP-6 as model DP-7. At this load, the superstructure showed some signs of deflection that constituted a slight amount of yield in the cross members on the ends of the lift. This deflection resulted in a slight yield in the cross members on the ends of the lift. The reason this member yielded was due to the mounting holes for the caster option being too close to edge of the tubing as cross members. The manufacturer observed the problem and stated a smaller hole could be used that would result in less of a stress concentrator. The cross member is plenty strong to hold the loads with no stress concentrator, so with this modification, the member should have no problems holding the load with no deformation.
With information supplied by the manufacturers of the cabling system, it was determined that the provisions of paragraphs 4.3.1.1, and 4.3.1.2, and 4.3.1.4 are all within compliance. At a load capacity rating of 7000 pounds, the cables will see a load of 1750 pounds each. At a strength factor of 5, the load carrying capacity necessary would be 8750 pounds for each cable. American Rigger Supply manufactures the cables for Cytech, and sent burst strength data which stated that the cable and end connectors had a strength to failure of 15,830 pounds. This nearly doubles the strength factor of 5 required for the cables. The provisions for the hydraulic system are described in the paragraphs of section 4.2. The pumping system is purchased as an auto-lift power supply, manufactured specifically for use on automobile lifting devices. The manufacturer of the pumping units will need to be contacted to ensure that the units are up to the specifications in this standard.
Paragraph 4.1.10 provides for a maximum speed of lowering the load to the floor level to be 20 feet/minute. The pumping unit has a built in flow restriction of 2 gallons/minute. With a cylinder of 3 inch bore and 1.25 inch piston, the area the fluid acts on is 5.8414 inches square. One gall is 231 cubic inches and the cylinder moves 1 inch per 5.8414 cubic inch of fluid. At this pace, the DP-6 lift will lower the load at 6.59 feet/minute. This is well within the maximum of 20 feet/minute.
For paragraph 4.3.1.5, the standard calls for a brake that will stop the lift from falling in case of a cable failure. This is a four post lift mechanism that has 4 independent and separate cable systems that act as redundant systems. If there is a cable failure on one post, there are three cables that will act to break the load from falling. Even if two cables break simultaneously, the cable strength is still strong enough to prevent a collapse of the load.
All hydraulic hoses and fittings are purchased parts that conform to the standards set forth for the safety of users. The manufacturer of these items are responsible to ensure conformation to applicable standards. MAMTC Return to Top Mid-America Manufacturing
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