The sportsmen club I belong to has a 1965 Cat D7 that the pony motor wouldn't start so it sat for over three years. Another member had his dozer repaired by a GREAT heavy equpment mechanic so the club hired that mechanic to get the dozer running. He did by sanding the points in the magneto with 80 grit sandpaper and it fired right up! The object of getting it running was to get the old girl on level ground to be able to safetly work on it. The club president decided to convert it from a pony motor to an electric starter. The heavy equipment mechanic pulled the pony motor and bolted the new electric starter up. BUT, that's as far as it's gotten! I've been fabricating blank off plates for the intake and for the coolant connector block between the cylinder heads. BUT I've run into a brick wall with getting the correct gaskets! I asked the Cat dealer where to look for a model number on the dozer and I can't find ANY of data plates in the places he said to look! I did find one data plate on the left side of the engine block at the back side of it. Said number is 48A6120 . Does that mean anything? I'm at the end of my rope trying to find gaskets for the old girl. PLUS I'm at loss as to what size cables to run from the batteries to the starter. The heavy equipment mechanic said we needed at least 1600 to 2000 CCA batteries to start it. What gage cables are required to carry that much amperage? I think it should have a positive cable disconnect so that the power to the starter can be disarmed when not in use or in case the starter stick on. Where can I get a disconnect switch that'll handle 2000 CCA? Any and all assisance will be greatly appreciated.
Hope that helps.
Not sure what kind of a gasket you need but if you need a flat paper type gasket they sell rolls at the auto parts store. You lay it on the part then gently form it with a small hammer and knife.
Check Break: Thanks for all the information. I'm going TO the local Cat dealer to get the parts myself = I've been depending on other people to get the right parts plus talking on the phone to sales people there. Georgia Iron: As for making gaskets, I have a "gasket maker kit" that I acquired many years ago from McMaster Carr. It consists of punches, a punch plate, and a circle cutter. I've tried to avoid making them myself but I can if it comes to that. I've also made gaskets with a ball peen hammer = you lay the gasket material on the surface that you need a gasket for and gently tap around all of the surfaces. A pair of gaskets that I've fabricated come to mind = small block Chevy water pump gaskets (can NEVER find them in the garage when you ABSOLUTELY need them!). Once I get things squared away here at home, it's off to the Cat dealer to (hopefully) get the right gasktets.
2000 amp is a serious switch (intermittent rating) Try a Cole-Hersee #75908 (single pole) The disconnect switch is usually placed on the negative lead on Cat equipment.
Yes the disconnect should be on the negative cable, the starting motor will use all the amps and won't pass through the switch.
If you look in the back of your parts book there will be a list of every thing you need to switch over to direct start. Bob
Gee, and I usually agree with you... If that worked, the ground cable would be 22ga. All the power has to go through both cables. Technically, the electrons pass from the battery through the negative cable, and return to the battery through the positive.
Went to Milton Cat and got the gaskets (that look a lot like small block Chevy water pump gaskets!) right away BECAUSE I had the D7's model number (48A6120) with me! Imagine that! Plus I had the transfer block with me (it connects the front and rear cylinder head water passages together) which has a casting number on it so they were able to find the microfiche that that block resides on = the gaskets another way! One minor problem: the line that ran from the block to the pony motor used an o-ring which I'm pretty sure won't work with my blanking plate. So, I stopped at Advance Auto, got the commercial accounts person (I do NOT trust the front counter personnel unless I know them) who got me the correct gasket material. I fabricated a gasket (with the use of my gasket maker kit and a SHARP pair of scissors) and, voila, I have a gasket for the blank off plate. Now for the disconnect switch: Cat has one part number for all their equipment’s battery disconnects which is 7N0718. I question the thought process behind installing the disconnect in the ground (negative) cable. I am an electrician by trade (among many other skills). I learned in the U. S. Navy aviation electrician mate school that the total power IN equals the total power OUT = the amperage draw on the positive cable (or power cable) is equal to the amperage draw on the negative cable (ground cable or neutral) AT THE POWER SOURCE (in this case, the battery). So the reasoning that putting the disconnect on the ground (negative) cable will minimize contact arching is incorrect. They might have another reason but I cannot fathom what it would be. I have been a participant in organized drag racing for many years. When your relocate the battery to the trunk (for better weight transfer) you must install an electrical disconnect switch on the positive lead of the battery. So I’m a little confused as to why Cat has the disconnect on the negative cable UNLESS it’s a carryover from the old theory that electrons flow from the negative of the battery to ground and then back to the battery. IMHO, the disconnect should be as near to the positive lead of the battery so that power can be immediately removed from all systems but that’s me.
I think the reason cat puts it in the negative, is so that if there's a problem, i.e. an arc at the moment of disconnection melting the switch, cable end melting off, etc. the problem will be on the grounded side of the circuit, and it won't matter what any loose parts touch; also the terminals on the switch are open, and it won't matter if something touches them. Functionally, it doesn't matter, because if you disconnect either side, you disconnect the whole circuit.
Not all, the 773G truck we have has a disconnect switch that is p/n 237-7602 This is a combination dissconnect swith and jump start receptical all molded togeather!
Check the rating on the 7N0718 switch. It is not rated for 2000 amp intermittent. I'd have to dig around and check but if I remember correctly it's more like 1000. The big 8D batteries are rated at 1500 amp cca.
The 7N-0718 is used on electric-start 994's that have 6 x 1500CCA 8D batteries wired in parallel and powering 2 50MT starter motors that swing that 3516 plus all the parasitic load of hydraulic pumps, etc, over with no problem. We replace ours only when we do a major re-harness & component change out programme at 22,000 hours. I can't recall ever replacing one that failed electrically, even if they get a bit stiff a good squirt of WD40 usually fixes them. It ought to handle whatever current a D7 starter draws .............
Mitch, you know how I like to preach, but I can pray, I have to figure this out now?
IF my 66 year old memory can remember back to my days at NATTC Jacksonville, Fla when I was in AE A school in 1968, there are two methods of describing electrical flow. One is conventional (electrons flow out on the negative and return on the positive) and electron flow (electrons flow out the positive and return on the negative). BUT both schools of though agree that for all intents and purposes, electron flow out equals electron flow back = there is the same current/amperage on both the main power and ground cables.
Holy Cats and dogs! I guess that disconnect will be OK on the old girl D7! Thanks for the feedback as I was worried that I'd be spending MORE time that I don't have looking for another disconnect! LOL!
UPDATE from two days ago: I had an IBS attack which prevented me from working on anything much less the D7. I went up to the D7 as the heavy equipment mechanic (HEM) was there and the club president wanted to know what I was doing. I related that all I was tasked to do was install the blanking plates and plug unused holes from the pony motor removal. Nothing more. My understanding was that the HEM would reassemble the D7 and install the new starting circuit as he knows what goes where and I don't. I also asked the HEM what the electric start circuit would look like. He explained that there would be three circuits: 1) from battery to the starter with the electrical disconnect on the ground wire. He said that's the way he was taught and it hadn't failed him yet. If it isn't broke, it doesn't need to be fixed (which works for me). 2) a starter key switch that will activate a (Ford style contactor) to supply power to the starter solenoid. Said solenoid will handle the 2000 CCA to the starter whereas the starter switch can't as it isn't rated that high. 3) A pushbutton that supplies power to the "S" terminal of the starter's solenoid. That power comes from the starter key switch. I'm happy with what he described as it will be safe and definately a robust installation. Again, thanks to all for your imput.
GraySkull, If it would help I could send you a wiring diagram for a direct start D8K that should be good for your D7. It does have some extra bits like A/C and heater but those can be ignored. I'm guessing your engine does not have glow plugs, not sure but this maybe a problem if wanting to start in cold weather we will be having soon here in NYState Seems like some engines had the prechambers with plugs in the holes where the glow plugs would be installed.
Sounds fine but the solenoid/start circuit (coils) do not see the 2000 cca. That's just the available amperage across the contacts. However there does seem to be a trend to use a solenoid on the start circuit to reduce voltage drop at the starter.