difference in gauges question

[creamgorilla]

What is the difference between electric and mechanical gauges?

[Twentyover]

I'm assuming you are asking about differences in operation

An electrical gauge uses, in it's simplest form, a permanent magnet located in a wire winding. As electricity is fed through the coil (wire windings), it forms an electromagnet, and pushes the permanent magnet into a position. The electrical gauge includes includes a sender, to measure the specific feature being gauged, that controls voltage driving the gauge coil.

A mechanical gauge usually uses has a component called a bourden tube. It's basically tube with roughly an oval cross section wound into a partial circle. As pressure in the tube rises, the bourden tube tries to straighten out. One end of the tube is attached to a gear train attached to a needle. As the tube tries to straighten, the gear train spins the needle. The tube is pressurized directly from the source when measuring pressures like oil pressure. When measuring temperature, the tube and a lead to a sensing bulb is filled with a fluid with a high coefficient ofthermal expansion. Since the fluid is in a sealed system, as temperature increase generates a pressure increase in the system. Again, the bourden tube tries to straighten out, driving the gear train attached to the needle

[creamgorilla]

OK yes that answers my question. Is either better than the other or is it just a matter of preference?

[Twentyover]

Historically, mechanical gauges were preferred by some because they were capable of 270 degree sweep (although many were only 90 degree sweep), and therefore, if calibrated correctly had the ability for greater precision and speed of recognition of the gauge measurement. Downside was you had to run a mechanical tube from the gauge to the engine/trans/diff.

Electrical gauges are easier to install (running a wire rather than a tube that can kink and break), but traditionally were limited to 90 degree sweep. There are some 2 5/8" electrical gauges available today with 270 degree sweeps, so the argument about precision can be, I guess, argued.


I'm going to posit that there are accurate electric and mechanical gauges and not so accurate electric and mechanical gauges. Determine how accurate you need them to be, and purchase accordingly.

[creamgorilla]

OK thanks. I appreciate the info

[Classic Nova & Performance]

With advancments that have been made with the electronic gauges and senders I think the accuracy issue is more dependant on the quality of the gauges than whether they are electronic or mechanical.

Walt