Monday, August 31, 2009

REPAIRING A MAXWELL NILSSON VR-700 WINDLASS PART 3

So I've removed the VR-700 windlass out of the boat. It has two problems:

1) The shaft does not spin when the windlass is under a load.

2) Following the lightning strike the motor only turns in one direction.

I decide to investigate the motor problem first. The motor has only two electrical terminals on it. At first I assumed one must be ground and the other the positive 12 volt terminal. But, then I wondered how do they get the windlass to reverse direction? Perhaps they reverse the polarity of the terminals. Though that would require some tricky switching to make sure the relay contacts never short out if the did there would be lots of sparks before the breaker tripped. So I hooked up a hefty 12 volt protected power supply to the terminals and then nothing. I reversed them and still no movement. This was puzzling the windlass motor was working in the boat at least in one direction.

I then had a hunch. Suppose the terminals are both 12 volt positive terminals. But, depending on which terminal is energized with the 12 volts determines the direction of the motor. There were no other terminals on the motor so that would mean that the motor case would have to be ground. I touched the ground wire to the case while the positive lead was connected to one of the terminals and motor sprang to life. I moved the positive wire to the other terminal and the motor turned in the opposite direction. My hunch was correct. So now I have confirmed the the motor is working in both directions so the lightning strike had not damaged it. But, the strike might have just damaged one of the solenoids in the windlass circuit. That was something could be easily replaced.

Now it was time to move onto the problem in the gear box. As I have mentioned I'm not well versed in mechanical things. But, perhaps maybe the gearbox problem could be a simple fix. So I opened the top cover:

Yuck! What a mess of grease and gears. So now I start to delve into the gear box myself. I put on some Nitrle disposable gloves and with some heavy duty shop paper towels get most of the dark grimy grease out of the gear box.

I notice the stainless steel shaft is loose in side the gear and see there is what is called a roll pin that goes through the gear then the shaft and to the other side of the gear. This pin is meant to break when the windlass gets under to much strain. Such as when a crew member steps on the deck switch when the chain is wrapped around the Sampson Post. It did it's job and gave me hope that this should be an easy repair. But, when it comes to boats that is sometimes just wishful thinking. As I soon found out.




The problem now became how to get the roll pin out. I first used a punch to try and knock the broken roll pin out. This was only partially successful. I was able to get a piece out but, not the whole pin. The problem is the case of the gear box made me have to use the punch at an angle and was not able to knock the whole pin out. I also noticed that there was actually two pins involved. One smaller pin inside the other. It appears someone previously had repaired the windlass and instead of replacing the defective pin they had simply inserted another smaller roll pin inside the damaged larger pin. It appeared to me that the stainless steel shaft should just lift out once the roll pin was removed but, something was keeping me from removing it completely.



I soon realized that I would have to remove the gear that the shaft stainless steel slid into to make this repair. A fellow Nonsuch owner provided a gearbox diagram of a windlass that he had which is for Nilsson model s400, s600 and s800 windlasses. But, the layout was very similar to my Maxwell-Nilsson VR-700. You can see it here . It help me to see a little more clearly what was involved. The only thing I could see doing was to remove the motor by unscrewing it from the gear case which would also remove the worm gear away from the gear and allow me to remove the shaft and gear from the gear box. So I tried using these:
A number of years ago I bought the largest Sears Arc Pliers I could buy. Mine are about two feet long and the jaws can open up to about 8 inches. I forgot why I bought them but they come in very handy for repair issues like this. I put windlass gearbox in a vice and gripped the motor with these pliers and tried to turn it. I was able to turn the motor slightly and then it stopped. I tried several times with no success. From the diagram it looked like the motor should just unscrew. I was stumped. But, I know enough about mechanics that trying to force things usually ends up being a bad move.

So I go on the Internet and find a little nugget of information that was crucial in a discussion on a cruisers board. It was mentioned almost in passing that a person recalled vaguely that there was a pin that had to be removed to remove the motor. Hmmm, pin holding the motor? There is no such pin on the parts diagram I had. Then I remembered the grease spot on the bottom of the gearbox when I was removing the windlass from the boat. Could it be? I removed the cover of the gear case and put a roll pin punch  into the hole where the grease stain was and with a few taps a roll pin emerged from the bottom of the gears housing.

NOTE: It seems this roll pin secures the motor threads to the gear case to prevent the motor from unscrewing when under load. That is why when I tried to unscrew the motor I could only move it a little. This is a crucial piece of information to remove the motor. With the pin removed I could unscrew the motor and the worm gear and finally remove the gear and shaft from the housing. Now that I can finally remove the gear and shaft from the gear box and I can completly remove the broken roll pin and hopefully get this windlass working again.

2 comments:

JamesNilsson said...

The two pins were standard factory parts. Originally these winches were power "in" only. Double pin was introduced to give more strength when reversing motor was introduced. Watch for spacer at end of worm shaft. Fill with 00 grade semi fluid grease to vover bronze worm wheel
Regards 'www.jamesnilsson.com"

Capt. Mike said...

James:

Thanks so much for the info about the second roll pin and other info. I will add it if I ever need to get into the gear box again. So far all is well with the single roll pin. Since I changed out the steel key that a previous owner installed with a softer metal. I have not had any problems that required another dismanteling of the windlass.