US Patent 7120523 Hydraulic cylinder life prediction

Maintenance requirements for hydraulic cylinders used to actuate heavy equipment may be predicted by measuring actual use of the cylinders. Sensors measuring piston position within each cylinder are integrated and the results stored in histograms bins to provide a permanent record of motion. Hydraulic pressure and temperature are also recorded. Data are downloaded periodically and compared with data from laboratory tests and/or from other units in the field.