The relays were common automotive types but operated on 24 volts. Basically five separate spades that have standard numbers. Number 30 is always hot and with the switch closed it power number 87A. Number 86 is the signal connection which powers an internal coil that grounds through number 85. When there is power at 86 the switch cycles to spade number 87. What was great on this installation is that the buss bars under the relays are all numbered to correspond to each relay. If you make the photo larger you can see what I'm talking about. Note that the one relay has a copper mounting lug. I got that from the local Napa store. The relays are set up to operate many of the machine functions but they also provide safety systems to shut off the engine down. I got all the electrical stuff working last Friday and then the drifter wouldn't go up or down. I noticed the chain would flinch a little and the hydraulic hoses jumped so the electrical was working. I looked at the chain and it was rusted pretty bad. I coated it with penetrating oil and graphite chain lube and let it sit over the week end. Went back this morning and worked it up and down till it was free. I drilled some holes in rocks to check things out and all worked as it was supposed to. Texted the owner and let him know the machine would drill rock again and to make sure and let me know when someone was going to run the machine so I could show them the level checks to make and how the controls worked. Maybe that will happen and maybe it won't.