PT1445 20 hrs, Lost steering!

[MossRoad]

David,

I had a gas cap which had a float and indicator which gave you the quantity of the fuel in the tank. What it amounted to was a spiral shaft with a float that slid up and down to indicate fuel level. The same principle could be applied here. A float that can handle hyd fluid. A spiral shaft, that is equivalent to the depth of the tank, that will give one full turn from empty to full. This can be determined by the number of turns on the shaft. otherwise, when the float is at the bottom, then the indicator would read empty or low, and when the float was at the top of the full level, the indicator would read full. This could also be done electronically, by using something like the lever float in a regular gas tank, empty to full. You would think someone would have done this by now. That gives some of you technicians out there an in site to come up with some something that could be adjusted for the level of different tanks.

I have a couple of those gas gauges from an old Simplicity lawn tractor. One is a long shaft and the other a short. The hard part would be rigging it up to read from the operator's station, so, instead of rigging something up, there should be some electronic fuel or oil level sender unit out there on the market already, I would think. It wouldn't have to read full depth of the tank, just down far enough to let you know there's a problem.

 

[MossRoad]

Would a fuel gauge and sender unit work in oil?

 

[MossRoad]

This is kind of neat.
AE LOW OIL LEVEL SENSOR from Aircraft Spruce
But it has to be mounted from underneath, so it would not be a good choice for us PT users as it would get scraped off.

 

[J_J]

Years ago when I was an electronics technician, we used to put thermistors on the oil dipstick, to indicate whether the oil was low. It worked by reading the resistance of the thermistor. You had to build a circuit and calibrate it for your car. In hot oil, the meter read OK, and if the oil was low, the meter read low. It worked by the fact that hot oil is hot and changes the resistance of the thermistor, and when the oil was low, the thermistor was in warm or hot air, and read a different resistance. Using a VOM and a thermistor, you can do the same thing.

How do those tire pressure sensors work, that remotely, tells you that the tire is low on air .

I just thought of a way to indicate low fluid, using something similar to the above. Those indoor and outdoor temp readers with remote sensors, the remote unit would be located in or around the hyd tank fill cap. a lead from the remote could be placed in the tank inside a protective sleeve, and set for a certain depth which would let the operator know if the fluid was low. . This way, you would know the temp of the hydro fluid, and also know when you were getting to the critical point. Sometimes I amaze myself, and sometimes I just don't

 

[Marks481]

This is kind of neat.
AE LOW OIL LEVEL SENSOR from Aircraft Spruce
But it has to be mounted from underneath, so it would not be a good choice for us PT users as it would get scraped off.

You could use that upside down, so the switch shutting when the float hit the end furthest away from the NPT plug activated the alarm.

That way you could mount it to the top of the tank. When the oil level fell to about 2" below the top, the alarm would sound. Of course, that is probably not enough of a drop to avoid the alarm becoming annoying.

And since it is made for airplanes, it carries a 50% markup over what it should cost....

A quick look on ebay reveals (to my surprise) that this is not that rare of a device; cheap $20 models for camero, bmw, vw cars and yamaha outboards are also available.

here is a Jeep version (ACDelco #1973) for $25 on ebay or $40 at Amazon:

 

[MossRoad]

You could use that upside down, so the switch shutting when the float hit the end furthest away from the NPT plug activated the alarm.

That way you could mount it to the top of the tank. When the oil level fell to about 2" below the top, the alarm would sound. Of course, that is probably not enough of a drop to avoid the alarm becoming annoying.

And since it is made for airplanes, it carries a 50% markup over what it should cost....



A quick look on ebay reveals that this is not that rare of a device; cheap $20 models for camero, bmw, vw cars and yamaha outboards are also available.

Yeah, I was poking around and saw those for GM cars. Interesting. I ownder if they need any external circuitry?

 

[MossRoad]

How do those tire pressure sensors work, that remotely, tells you that the tire is low on air .

They use a proximity switch that counts pulses on the tire rotation. If the tire loses air, it gets smaller and has to rotate faster. That changes the pulse count. I'm pretty sure it is the same sensors that the anit lock brake systems use to see if the tire is rotating in a skid.

 

[Marks481]

Different companies probably have different ways to implement the pressure sensor.

Suburu uses pressure sensors mounted in place of the valve stems, that transmits the pressure every 30 seconds while the tire is rotating. Battery is rated for 10 years/ 100k miles.

Subaru Tire Pressure Monitoring System operation

 

[J_J]

What if we were to mount something like the Subaru tire transmitter, and pressurizes the tank, and when when full, max air pressure, no signal, but when tank is one half full of fluid, less air, a signal is transmitted to the dash, and maybe shut off the engine.

 

[Marks481]

I wonder if they need any external circuitry?

I am sure that it is just an on/off switch. Unfortunately, the length of the float slide isn't really long enough for our hydraulic tanks. You would have to fabricate some sort of well extending down into the tank to mount those. Maybe use 1" diameter tubing with the npt threads on the end so the sensor is mounted in the bottom half of he tank.

That sounds like more work then it is worth, since I am sure somebody makes a similar device for hydraulic tanks with a longer slide. Of course, since they don't get mounted on millions of cars, they aren't $25 either (and you don't find them on ebay).