Confused about oil pressure switch and sensor

[clinter36]

I have a detroit 4-53 in a old Bantam Excavator. It runs great and still pops rocks out of the ground and its plenty capable of making a huge mess.

I was going to clean up some wiring and get the gauges properly working again but I am a bit confused on the oil pressure switch wiring. Sorry the image below is not that great (you can check out page 65 on the pdf if you really want to look at a better copy).

If you notice terminal B on the regulator goes through the oil pressue switch (and separately through a breaker on to the amp gauge and then the key switch) and then appears to power the other gauges via the oil pressure gauge. The oil pressure gauges gets a pressure signal from the oil pressue sensor. What would be the purpose of powering the gauges through and oil pressue switch ? (except to really confuse you if you lost oil pressue).

Any thoughts or words of wisdom ?

My intention is to replace the amp gauge with a voltage gauge and figure out why the oil pressure gauge seems to start at 50psi and get that corrected.

Thanks

 

[Deimos]

What would be the purpose of powering the gauges through and oil pressue switch ?

I think the goal is that when there is no oil pressure, the hour meter will not work, and it will also stop showing the temperature and fuel. And so that during work the operator would immediately see that he has big problems and no oil pressure. But I may be wrong. Maybe someone has other ideas?