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C I Mention was made in CM, March 13, of a strain-gauge
Page 99
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load-sensing device, the Ax-Way. As the author of the article says in his first paragraph, numerous attempts have been made to produce an acceptably accurate and reasonably priced weighing device that can be carried on the vehicle and have been reviewing the possibility of producing a device that might compete with this system.
I have evolved an electrical unit that basically comprises a coil-and-lever mechanism linked to the axle. The coil is connected to the battery and to a gauge, and as a contact point on the lever moves across the coil its resistance is varied according to the deflection of the axle and a load reading is given on the gauge. Low cost and simplicity are advantageous features of the device and it should be cheap to produce. What is your view?
A While the load-sensing device you have ^ evolved is sound in principle, it would normally have a very short life because the lever would continuously be moving across the coil and the wear rate would be high. And it would be essential to exclude mud and moisture from the contact area, which might be a difficult problem as the unit would normally be located in an exposed position,
A variable-resistance load-sensing device was mentioned in CM. September 20. 1968, which has an advantage over your device in that the arm carrying the contact point is held away from the coil (in this case a resistor winding) during normal running. A springloaded solenoid is used to bring the contact point and the winding together when a reading is required and the unit is fully enclosed in a telescopic member. The system was evolved by Mr M. J. Carthew, of Al Shaws Caravan Site, Pinfold Lane, Aldridge, Staffs.
The fact that the winding is not in contact with the contact point when there is movement between the two parts should give it an indefinitely long life. A strain-gauge sensing element has the outstanding advantage that it operates at all times without relative movement of two or more component parts and it should have an indefinite life. It should also be immune from weathering.