ISOLATION LEVER AND “FMSS” MASS-COUNTERBALANCE

Unique technology provides isolation from all force vectors except material weight

THAYER belt scales use a multiple lever design to mass-counterbalance dead weight and to minimize the effects of extraneous forces that would alter the weight measurement. The patented rocking-flexure primary pivot design minimizes effects of idler friction, structural deformation and distortion of the conveyor.

Thayer employs a secondary lever system, even though it costs more to do so, because it permits us to do the following:

We can add mass to counterbalance the dead load (frame, idlers, belting) – and, by using a secondary lever, we do not load down the suspension pivot.
By positioning the load cell correctly, relative to the secondary lever, we can match an available size load cell range to the net loading on the scale. Only in this way can any capacity scale be supplied to the same high standards.
The resulting increased lever ratio of the secondary lever reduces idler friction, providing additional immunity to errors associated with belt tension.

The secondary lever system utilizes stainless steel aircraft cables as flexural elements to transmit and focus purely tension forces to the load cell. The cables, being non-extendable, but laterally yieldable connecting links, permit the lever to align itself under conditions of varying distortion. This is a most significant feature. Remember, conventional platform scales are normally supported on concrete pads to eliminate all structural distortions. A belt scale, on the other hand, must use the conveyor stringers as its mounting base. These stringers not only deflect under varying conveyor loads, but may also rotate (or twist). A suspension system having the least possible structural redundancy is therefore essential.

The scale provides for complete mass-counterbalancing of the dead load (idlers and belt) of the conveyor permitting the load sensor (strain gauge or LVDT) to react only to the NET material load. This unique system is not affected by dirt, shocks or vibration, and can withstand overloads in excess of 1,000 pounds without causing damage or affecting calibration. The highly advanced and extremely robust sensing technology is based on the marriage of the weight transducer, embedded temperature sensing and proprietary linearizing and temperature compensating algorithms.

LOAD CELL UTILIZATION FACTOR
The performance of a load cell and its instrumentation is specified on the basis of the load cell’s rated output. If the load cell is supporting a quantity of dead-weight (i.e. idlers, belting, suspension system) and has been further oversized to accommodate problems of overloads, off-center conveying, shock and vibration and negative integration, then the amount of range left to do the job of weighing is only a fraction of the cell’s rated output. The percentage of the load cell’s rated output reserved for the actual job of weighing material is called the LOAD CELL UTILIZATION FACTOR.

Thayer “RF” Belt Scales with “FMSS” Force Measurement Suspension System mass-counter balance technology assures better than 80% Load Cell Utilization.

Provides :

Field adjustable mechanical TARE balancing of dead loads typically as high as 200 times NET loads, thereby providing the full utilization of the load cell force range.
Reduces deflection of load receptor to a fraction of load cell deflection.
Reduces zero shifting as a result of foundation distortion.
Provides preferred access location of load cell for inspection or removal.
Simplifies the application of test weights for calibration/performance verification.
Provides for lower signal velocity and acceleration under dynamic conditions