Ford 4400 TLB Hydraulic Failure

Just before dark I fired up my old 1965 Ford 4400 to push together remnants of a burning brush pile and while pushing the last side, I lost all hydraulics; working one second and not working the next. I was able to back away from the pile letting the front bucket drag along. Using a flashlight I checked around for signs of a busted hose. Having an old machine, I am not a newcomer to busted hydraulic hoses. I saw no signs of leakage. I did notice a noise that was not common. I later discovered the noise was generated by the crank pulley mounted splined hub; the hub splines were damaged and skipping over the splined pump drive shaft.

The backstory is: I bought this machine in late 2009 with the diesel engine of course running good, but the hydraulic power was weak. I found the Vickers Vane Pump input shaft had lots of excess play and pulling air in to the hydraulic system. Initially I was going to rebuild the pump, but after talking with Zip Underwood in or near St Louis, I purchased a new Vickers pump for around $325. I also replaced the pump drive shaft at this time, but did not realize the pulley mounted hub required inspection. I thought the crankshaft was bored and splined. Good thing that is not the way it is done.

So back to today, I disassembled and found the crank pulley hub splines 99% gone. I also noticed the end of the pump shaft splines are a little buggered up. Looks like not enough engagement there. I also noticed I must have (in 2010) pressed the 3 inch coupler too far on the drive shaft, not leaving enough for pump input shaft engagement. As for the splined hub? Probably just a sacrificial part since it is 52 years old.

I checked and can purchase the crank pulley splined hub (C5NNN879A), pump drive shaft (291951) and Splined Coupler (7707570) from Yesterday's Tractors. During reassembly I think I can manage the assembly stack-up to get more coupler to pump input shaft engagement this time. With more engagement, the pump input shaft spline may be OK, but not sure. Since the pump is only 7 years old and I just use it occasionally around a small homestead everything else about the pump is like new. I could purchase a new pump shaft and install it. What do you think? Should there have been something behind the hub bore to keep the shaft from retracting from the pump so much (still engaged, but not enough) when the hub splines failed? I realize the failure had been building and the degrading spline problem probably built up burrs that was driving the pump until that moment of failure. Upon failure, did the drive shaft retract the coupler off the pump shaft some?

1965 Ford 4400 TLB
Production Code: 5K26C 1965/Oct 26/Afternoon Shift
Model # 44011C: 4000 Series/Utility/Diesel/No PTO/8 speed
Serial # C1445201296
Backhoe Model 753 Series Loader Model 735 Series

Current 2010 Vickers Pump V20-1S-13S-23A-20-L 13 splines ccw rotation shaft diameter 0.868


<image src="http://forums.yesterdaystractors.com/photos/mvphoto6491.png"/>

<image src="http://forums.yesterdaystractors.com/photos/mvphoto6492.png"/>

I would do just as planed.

Reuse the pump shaft, and get full engagement into the drive shaft.

Then be sure the drive shaft also gets full engagement into the coupler.

If necessary, space the coupler further forward, and it may be necessary to put something behind the drive shaft to keep it from walking back too deep into the coupler. Be sure to put some heavy weight grease on the splines on final assembly.

Hard to tell without seeing the big picture, but keep in mind, anything that can go wrong, will...

When you put it back together, put some good thick grease in/on the splines.

Rust/fretting of the splines is what "kills" them.

I appreciate the feedback and understand the advice about heavy grease helping to prevent fretting and failure of the splines. The stripped hub was dry as a bone. Still wondering if anyone has opinion about the small amount of engagement on the pump input shaft. When taken apart after the failure, the 3 inch coupler was 2 inches over the drive shaft and only 1 inch on the pump input shaft. when the drive hub splines gave way, the drive shaft would have been free to move toward the engine and leave very little engagement of coupler to pump shaft. I am trying to better understand what happened so I can hopefully prevent it for happening again. I am probably overthinking it and missing the obvious. The obvious is new hub and shaft coated in neverseize will keep the assembly stack-up in place between the 2 points. Thanks

I am the original poster and want to follow up with additional details since I have my new parts now. Remember when my hydraulic failure occurred, ends up the splines in the crankshaft pulley mounted hub had completely failed and allowed the drive shaft to move towards the engine. I can see the shiny place on the crank pulley bolt head. This drive shaft retraction left little engagement on the pump input shaft and buggered up the first ?" of splines on the pump shaft. Thinking this will be OK IF I can assemble with fully engagement of splines throughout assembly. The picture shows the pump, coupling, drive shaft and hub on a table top with full engagement at each joint. The threaded rod from the pump mounting plate to the first nut represents the distance from the crankshaft pulley face to the inside of the pump mounting plate it is bumped up to. My full engagement assembly is short by 5/8". In case someone wonders, the drive shaft is 13 1/2" long just like the original. I can fix this by adding spacers between the hub and crankshaft pulley; thinking ?" of spacer to leave 1/8" of play. Of course assembling everything in place will be harder to confirm amount of engagement at each joint. Table Top assembly was easy because I can "see" all of it. Am I the only person to run in to this trying to keep everything engaged and span the fixed distance? I don't want to ruin anything else. If this should be in the hydraulic section can I move it or would a moderator need to move it? thanks

<image src="http://forums.yesterdaystractors.com/photos/mvphoto7053.jpg"/>

I've made several spacers over the years to get more spline engagement. I would get a piece of 1/2" thick cold rolled plate, drill holes into the plate, and trim the plate down as needed. Then get some 1/2" longer bolts, and put it together. An 1/8" is enough to let the shaft float between the two couplers.