Ford 713 backhoe ,Re-attach swing cylinder swing link
I have a Ford 4000 Industrial tractor with a 713 backhoe and companion loader. This is the 1962-1964 tractor.
I"m quite sure that it"s the ugliest-looking backhoe on earth, but it works.
A couple weeks ago, one of the pins in the left swing link fell out. That, of course, stops the boom from swinging to the left because the trunnion cylinder can"t pull on it. I found the pin and thrust washer lying on the ground. I took the swing link into the shop and rewelded the pin in to its proper location. During that time, I found that the pin in the other half of the swing link (looks like a HUGE link of bicycle chain) had broken it"s weld, too. I fixed that. Then I set about putting things back together.
WOW! What a problem. I had no idea how complex the hydraulic circuit/controls are for the swing system on that tractor. There are two hydraulic devices between the main control counsel and the swing cylinders; the cushioning valve and the flow control valve. No way can you get oil OUT of one trunnion cylinder without hydraulic pressure applied to the OTHER trunnion cylinder!!!!
How to get the piston to come OUT of the trunnion cylinder so I could reconnect the link? I read someplace that you have to disconect the hydraulic line AT the cylinder and apply shop air pressure to it to push it out. Yeh, but I could not get to THAT cylinder, as there are several hydraulic lines in the way. I guess the guys the wrote the manual had the hoe off the tractor, but I was not about to go through all that. I tried several ways of pulling the piston out, with tractor running (very dangerous) and with engine off. I couldn"t get anything to work with engine off, but I could get the piston to come out a little by making an 8 inch long u-shaped link out of 1/2" round stock that would fit in both the cylinder"s piston hole and in the pin hole for the connector on the swinging assembly. Trouble is, I could not get the piston to come far enough out to install the connector. I"d try to partially operate the right cylinder so the pressure on the left cylinder would be released, but, no matter what I did, I couldn"t extract that left piston rod. Here"s the thing that finally worked:
-I attached one end of a come-along to the left cylinder"s pin hole and the other then to the stick, so I could pull on that cylinder.
-Then I started the tractor up and pushed the bucket into the ground not quite enough to lift the tractor off the ground.
-Then I VERY GENTLY started to swing right, while my son cranked on the come-along. This method worked very well to extract the piston rod from the left trunnion cylinder. I didn"t even have to put enough swing pressure on to actually move the bucket. With this process it was easy to get the piston rod out far enough the re attach the swing link.
Obvoiusly, a great lesson was learned from this. But another lesson is that I should NOT push the "swing"
all the way to the stops as I had been doing. I think the cam levers are adjusted okay, but I won"t be "testing" them so hard in the future.
I know this is a pretty old backhoe, but I hope this can help someone else,