Types of Scales for Forklifts and Loaders
Hydraulic System Pressure Transducer Scales
This is one of the lesser cost types of scales for a loader or forklift truck, however there are some limitations that need to be considered.
- Accuracy is not a strong point. Any pressure transducer type of scale requires calibration with a known load of the same size, configuration, and weight distribution as the loads that you wish to weigh.
- Accuracy is typically 1% to 2% of the maximum load weight that you calibrate it to. Thus, if the heaviest loads weigh 4,000 lbs., and if you calibrate the scale using a 4,000 lbs. load, the accuracy for everything you weigh will be 1% to 2% of 4,000 lbs., which means that the readout could fall between 3920 lbs. to 4080 lbs. The maximum variance is plus or minus 2%.
- If the loads to be weighed vary from the calibrated weight, the 2% variance (plus or minus 80 lbs.) will apply to all loads weighed. Thus, when a 700 lbs. load is weighed, the variance could actually be 11% plus or minus, or a scale reading in the range of 620 lbs. to 780 lbs.
- Another factor in the accuracy of the unit is consistency in lifting the loads for weighing. For best results, you must lift each load at a consistent and steady speed, to the same height, in order for the hydraulic system to react and deliver consistent pressure to the transducer. The scale manufacturers do the best they can with their software to sample the pressure in the hydraulic system hundreds of times within a second or two and "average" the pressure reading which they then translate into the weight of the load. But inconsistent lifting of the load can induce additional inaccuracies.
- Frequent re-calibration is needed in order to insure accuracy, so it is important to have a calibration load handy.