Diagnostics equipment provider Drakefield offers a variety of solutions for commercial vehicle applications, including a potentiometer testing device.
“Most truck EBS systems now days monitor the pad wear percentage, and when the pads get to a pre-set wear value the warning light or display on the vehicle’s dash will tell you the pads need changing,” said the company.
“This is great if it’s all working as it should do, but what if there’s a fault in the pad wear system somewhere?
“A few systems will actually then show an EBS light when there’s a fault, the pads get low or if there is an imbalance in the pad wear across the axle. This is okay, but what if the caliper’s potentiometer is faulty?
“In this case the common practice is to change the complete caliper, because in the past the potentiometers were not available as a separate part – but now you can buy the potentiometer and fit it yourself, saving downtime and money.”
The difficulty, says Drakefield, lies in how to set the potentiometer to the correct starting place.
“Without the correct tool, it’s nearly impossible to set a two- or three-wire potentiometer, as it has a voltage value that goes in an endless loop, which the EBS system is monitoring then equating the voltage to a wear percentage on your dash.
“A good example is a three-wire silver potentiometer: 1.0 volts = 100 per cent new pads; 2.75 volts =75 per cent worn pads; and 3.50 volts = 0 per cent or fully worn pads.
“When fitting a new potentiometer you will need to set it to 0 per cent. We use the Drakefield potentiometer tester which requires no training. Calibrating a potentiometer is intuitive with our tester; simply follow the on-screen display which shows you percentage, voltage and a bar graph.”
The tester is specially designed just for this job, says Drakefield, offering a quick, accurate means of testing the three most common types of potentiometers.
“All you need to do is select the type of potentiometer you are setting from the OLED display and turn the centre of the potentiometer until the bar graph is at 0 per cent, and the correct voltage is shown. It literally takes seconds.”
The potentiometer tester comes with two connecting cables, the Scania clip type and the screw-on type, and built-in batteries which are rechargeable via USB power, all in a small carry case. It is available from Drakefield, aide automotive and European Braking Systems.