Century® Online Trouble-Shooting Guide

CENTURY HYDRAULIC SCALES: In general, hydraulic scales require very little attention. The hydraulic load cell is comprised of a piston bonded to a rolling diaphragm floating over a cylinder of hydraulic fluid. The piston receives the load and converts that force (or weight) into a proportional pressure signal that is sent via hydraulic tubing to a bourdon tube type of dial indicator. Following are the few things that can cause a system to operate incorrectly:

Symptom: ERRATIC DIAL READINGS or NO RESPONSE
Possible Cause: LOW ON OIL
Because there is very little hydraulic fluid in the whole system, losing a small amount of fluid can affect the operation of the scale. If the hose or fittings develop a slow leak, it is possible for the load cell system to "go flat" or "bottom out" over a period of many years. Most times, there is no visible sign of leaking oil from the system. Typically, large fluctuations in dial readings is the first indication that the scale needs oil added because the piston is lifting up and setting down on the cylinder bottom as the oil expands and contracts with ambient temperature changes. All hydraulic load cells have a load cell filler plug for refilling with SAE 5 or 10 weight non-detergent machine oil. It is not necessary to "change the oil", but simply to "top off" the load cell so that it has a full charge of oil. A full or normal charge of oil is indicated by the piston extending ¼ inch (6 mm) above the cylinder of the load cell.

Symptom: OIL LEAKING FROM LOAD CELL
Possible Cause: BLOWN DIAPHRAGM
It is possible for the load cell diaphragm to rupture. This can be caused by dirt or sand getting down into the convolute of the diaphragm, or simply an overload shock from a ton container dropping onto the scale or an excessively fast overhead hoist (we recommend hoist speeds no greater than 18ft/min). Most times, a blown diaphragm is evident if there is a puddle of oil around the base of the load cell. This condition causes the hydraulic system to completely lose all pressure in the system, and the scale will not respond to changes in weight. If a torque wrench is available, it is possible to replace the diaphragm in the field by ordering our diaphragm replacement kit for the scale. Order now.

Symptom: ERRATIC DIAL READINGS
Possible Cause: FRICTION OR BINDING
For any scale to operate properly, plumbing or other devices must not restrain the tank or platform. In order to eliminate any friction or binding in the system, all tank supply or feed connections must be flexible. If there is any friction or binding in the tank connections, fluctuations in readings may happen due to the load cell being restrained from moving up and down freely as temperature and weight changes.

TUBING or HOSE LENGTH TOO SHORT
Sometimes you may find that you do not have enough tubing between the load cell and the dial indicator. If you have a quick connect fitting at the dial, it is very easy to add hydraulic tubing in the field by simply ordering extra hose. The tubing can then be extended by simply clicking the hose into the existing dial and tubing.

PARTS LIST: Usually the only required spare part for our scales is a can of 5 or 10 weight non detergent machine oil. Shown here is a typical parts list.