JD 4020 Part identification help

[Randy Kuhn]

First of all, please excuse my mechanical ignorance.
I"m looking at purchasing a 1964 John Deere 4020 Diesel.
The only thing that has me worried, was when i looked at the lower crank shaft that drives the fan belt from below the fan. There is an aluminum looking part with 2 "ear"s" on it that is suppose to be attached to another shaft that run"s under the radiator. One of the 2 pin"s on that part is half broken off the part behind it! What is that part, and what is the purpose of that shaft?
 

[mstas]

sounds like your talking about the hydraulic pump drive. It runs off the crankshaft pulley
 

[Randy Kuhn]

Thanks mstas,

I kinda figure that's what it was powering, but wasn't 100%. How much of a pain in the butt is that to change?
 

[rrlund]

Not TOO bad in relative terms. Take out two bolts and take the two halves off to get to the shafts with the rubber gromets. Then if memory serves me right,loosen a bolt that clamps one of those shafts to the pump shaft and it should slide off. I THINK the other rubber gromets just bolt to the front pulley.
 

[JMS/.MN]

Like rrlund says, but........check if there is a locking nut on the backside of each bolt. The bolts thread into the aluminum half, and some people, like me, put a nut on the back side for extra security from coming loose. Bushings are usually squished, new ones are round. Put new ones in.