For maximum safety, concrete placement booms should be inspected and tested regularly, overhauled when necessary, and operated by properly trained personnel. By following an established preventive-maintenance program, the likelihood of failure to the boom and related components can be reduced. It is almost always more economical to prevent trouble before it occurs.
When establishing a preventive-maintenance program for boom-equipped concrete pumps, it is suggested that a log book of maintenance history for each unit also be established. The log book should contain the serial number of the unit, dates of testing or inspections, results and subsequent repairs, and date of the next scheduled test or inspection. The following tests or inspections and frequency rates are recommended for placement booms: visual inspection every two weeks; load test once a month, static and dynamic test on a quarterly basis; and magnetic-particle inspection (magnafluxing) once a year.
To check holding valves and hydraulic cylinders, extend the boom horizontally from the side of the truck. With the test weight attached raise the boom slightly so each segment is supported by hydraulic pressure in the cylinders with the pressure against the holding valves. The cylinders should not be bottomed out. Carefully measure the distance from weight to ground. Turn off the power sources and leave the boom in that position for at least 10 minutes. Then remeasure the distance from weight to ground. There should be no downnward drift of the boom. Reposition the boom horizontally and remove the test weight. Move the boom up and down and bounce it by stopping abruptly several times. Reattach the test weight and repeat the drift test. If the boom has drifted downward the holding valves or hydraulic cylinders are leaking and need to be rebuilt or replaced.