Just purchased an old Dayton 3z960 and I need help

by brady
(Richmond, Ca)

Dayton 3z960 wiring - 1

Dayton 3z960 wiring - 1

Dayton 3z960 wiring - 1
Dayton 3z960 wiring - 2
Dayton 3z960 wiring schematic

I just aquired a dayton 3z960 that was used for years in a Mercedes Benz dealership. The seller plugged it in and it fired up and gradually the pressure gauge climbed.

Right after I gave the gentleman his money ($500) he mentioned that it would need a relay to cut off once it reached full pressure.

I was flustered and had a dickens of a time getting it onto my little truck, so I was unable to clarify with him what he meant. I've tried to contact him and thus far I've had no luck.

I can see on the pressure switch that the central two terminals are "motor" and the outer ones are line one and two.

The wires coming out of the motor are bundled as they were when he plugged before selling it to me, so that should be in order.

Included are some pictures of what I'm up against. I understand that the pressure switch should cut the power. I purchased some cord, a plug, and a 220v switch (so I can turn it off without unplugging it), but I'm reticent to wire it to power if the pressure switch won't do it's job.

I would speculate that I need to wire the leads coming out of the pressure switch back in line with two of the wires from the motor? Do I need some sort of relay as the seller stated? Any help would be greatly appreciated. I have a job I'm trying to hustle out of my metal shop and I absolutely need this compressor as soon as possible.

Thanks in advance,


Comments for Just purchased an old Dayton 3z960 and I need help

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May 31, 2017
by: Doug in s.d.ca.

The switch is a good idea...

You can look at the furnas rating label - is your motor within the rating?

If so, go ahead and power it up. If it gets to pressure (did they tell you what that is?) and shuts off, great.

If not, then you need a magnetic starter: you wire the pressure switch motor contacts so they operate the starter solenoid/relay winding, and run power to motor through the starter contacts.

Just to be clear, the power for the motor comes directly from the cord, and not by way of the pressure switch.

Have fun and good luck!

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