Nicholas Fluhart

Well, after 30 years of service, age and wear had finally gotten to the hydraulic cylinders on my old Allis lift. You may remember previously I rebuilt the short lift cylinder and one tilt cylinder on the mast. Later, the long lift cylinder and the other tilt cylinder both began hemorrhaging. Bad became worse and soon I was loosing a gallon of fluid at every use. Fortunately, I had recently acquired a little Clark lift which took up most forklift duties around the complex. This bought me a little time for the repairs.

After the local hydraulic shop, in a state of incompetence, screwed up my short lift cylinder, I decided to rebuild this one myself. Rebuilding the long cylinder is no easy task for two reasons. One: Due to its location within the mast (not to mention its weight), it is heck to remove and reinstall. Two: It is also more complex than the short lift cylinder as the long cylinder has a feed tube with all the associated bushings and seals. At first glance, there’s no logical strategy for getting it out, and since my service manuals don’t cover anything to do with the mast, I’m flying purely on what I hope to be at least a moderate level of competence in terms of my skill level. Nevertheless, I endeavored to persevere.

Since I figured the mast would have to be raised at some point during the procedure, I had to work on it outside the shop. I began by removing the hydraulic line attached to the feed tube. Then I removed the nut that fixes the feed tube to the top stage of the mast. You’ll note that I’m using a manual ratchet instead of an air wrench on this because the nut is self locking, and often times if an air wrench is used, it will destroy the threads because of the high rate of speed.

Hydraulic Line Removed from Feed Tube

Removing Feed Tube Nut

Might I add, the humidity level that day, and throughout most of the project, had to have been 200% if that’s even possible, which explains the somewhat foggy photos and my drenched shirts. Moving on… Next, and before loosening anything else fixture-wise, I decided to loosen the gland nut while the cylinder was still firmly in place. I didn’t have a wrench big enough, so the next day I borrowed a large chain wrench which did the job nicely.

Feed Tube Nut

Loosening Gland Nut

Next, I had to raise the mast so I could lower the junction block at the top of the feed tube through the second stage of the mast. For this I took my Clark lift and raised the carriage on the Allis lift until the second stage of the mast begun to raise. This was NO easy task. The Clark lift would barely handle the weight. To make matters worse, the junction block is slightly offset and refused to go down through the hole in the second stage. Careful not to bend the feed tube, I pried and hammered a bit before logic struck at which time I decided to loosen the bottom mounting nut on the cylinder (exactly like the top nut on the feed tube). This allowed some wiggle room, and alas, it dropped through and the top of the cylinder was now completely free.

Feed Tube Junction Block

Raising the Mast

The next step in removing the cylinder was to finish the bottom mount and unhook the bottom hydraulic line, but first I made certain the mast was safely suspended. Don’t let the compact size of this machine and these parts fool you; this stuff is very heavy. The machine weighs about 13,000 lbs, and the mast components are made from very thick and very heavy steel. There is literally a ton of weight hanging above me here, so safety is very important. I used a strong, heavy-gauge pipe to hold the mast up, then I chained the top portion of the mast for a backup safety mechanism. I also had the carriage double chained.

Safety Check

When attempting to unhook the hydraulic line from the base of the cylinder, it became evident that there was not enough room to maneuver the wrench in the tight space. So I decided to unhook the line back at the hydraulic valve. This would give me slack enough so when I removed the cylinder I could pull the base out far enough to use the wrench to remove the line from the base of the cylinder. Back at the valve, I also had to unhook and move the hydraulic filter to have enough room to work at the valve.

Filter Moved Back from the Valve

Disconnecting the Bottom Hydraulic Line

Finally, the heavy cylinder was ready to come out.

Now that the cylinder is removed, it is time to disassemble the components for inspection at which time we can also take measurements which will be needed to order the new parts. We place the cylinder down where we can easily work on it and remove the main gland nut, and then the main ram easily pulls out of the bore. Then, using the same chain wrench, we remove the feed tube gland from the ram, and the feed tube pulls out. Then, although it’s not pictured, we removed the feed tube gland which proved to be extremely stubborn to slide off the tube, but a long pipe and a sledge hammer did the trick.

Loosening Feed Tube Gland

Removing Feed Tube from Ram

Once everything is apart I can begin measuring the components to place an order for new packing. I couldn’t simply measure the old seals because they had completely disintegrated. This explains the hemorrhaging, and it also explains how rainwater was entering the hydraulic system. Nevertheless, I took measure and proceeded into the office to do what the incompetent local hydraulic shop said was impossible: find new seals. After approximately one Google search and three minutes of viewing an online catalog, I easily found the parts I needed and placed the order. Since my application has a feed tube involved, it required the most expensive packing kit. This is largely due to the addition of bronze bushings and extra seals. However, it was still much cheaper than anything the local guys could have ever came up with and I was happy to find the parts. Now, on to the business of reassembling the cylinder…

First we took the feed tube gland and knocked out the old plastic bushings and replaced them with the new bronze bushings that came in the kit. We used the hydraulic press to install the new bushings:

Installing Bronze Bushings

Reinstalling the gland back on the feed tube proved almost as difficult as removing it. We used a brake cylinder hone to reach precisely the correct inside diameter of the bronze bushings, then we used a buffing wheel on a Dremel tool to polish off any scars on the chrome feed tube. After that, we were able to slide the gland back on the tube with moderate pressure. Then we installed the feed tube back into the ram, and after installing the new wear ring / guide band,  we reinstalled the ram back into the cylinder. Once completed the final step was to install the new oil seal and dust seal into the main gland nut.

New Oil & Dust Seals for Gland Nut

With new oil and dust seals in the gland nut, it’s time to install the nut back onto the cylinder, and it is a tight fit over the feed tube gland and ram. To keep from destroying the new seals, we placed a spacer on top of the gland nut and then used two bolts through two flat bars and threaded them into the top of the feed tube gland. This slowly pressed the gland nut onto the ram without damaging the seals. And that concludes the assembly of the cylinder.

Installing Gland Nut

Cylinder Assembled

Now, before reinstalling the cylinder onto the forklift, we needed to paint it. Jose uses a wire brush to strip all the old paint off. Then he masks off the chrome before applying primer.

Stripping the Old Paint

Applying Masking Tape

To conclude, I come in behind him with a new coat of gloss white industrial enamel. We then reinstall the cylinder in the same sequence used to remove it. The final step was to refill and bleed the hydraulic system and give the machine a good scrub and wash.

Applying a Coat of Industrial Enamel

Finished and Back in Service!

Everything worked out great bringing us to the conclusion of this project. My Allis-Chalmers ACP 80 is back to work and running great.

Until next time…

This is a followup on the short lift cylinder repair. To see the later hydraulic repairs, click here.

Overall, the hydraulic repairs on the forklift were a success. The cylinders that we overhauled aren’t leaking a drop. The only notable issue we now have is with the lift cylinder we installed the new packing in. Often times when new packing is installed the cylinder is a little more stiff in operation until the seals and such seat in. This may be magnified slightly by the seal modifications made by the hydraulic shop (see the original post). With a double acting cylinder, this is rarely even noticed. However, with a single acting cylinder like the one I am dealing with, it can complicate operation.

The Issue: The cylinder powers up fine, but until the packing wears in it has made the cylinder a little too stiff for gravity to pull the forks back down. So when I pull the lever to lower the forks, they don’t move. Typically, what goes up must come down. Not so anymore; it’s a one-way street. The only way to get them back down is to apply a load of at least 300 lbs.

Solution: The more I use the forklift, the better it gets. However, since I only use it occasionally, it may be a substantial amount of time until the cylinder wears in. Until then, I’ve developed a short term solution. First, I added fork extenders. This is a two-fold benefit: it gives me additional fork reach, and it adds about 150 lbs to the forks which helps my cylinder issue. Second, I added about 330 lbs of low-profile weights to the forks.

These are actually some type of linkage component, but they weigh 11 lbs each and they are slightly raised on one end making them stack together perfectly. I purchased about 75 of these for less than a buck a piece at an auction with this specific purpose in mind.

I calculated that I could stack about 15 of these on each fork and place them directly at the base. I placed an axle through each stack with a close diameter to the holes in the weights. This holds them stacked and in alignment even when they get bounced around. I then used winch cable to tie each stack in place.

Success. So far, it’s proven to be a good solution to the short term lift cylinder issue. I’ve used it to load a variety of types of materials ranging from crates to scrap iron and the cylinder operates better and better all the time. The low profile weights keep them out of the way and the extended forks more than make up for the used space. I can comfortably leave the weights on the machine indefinitely until the cylinder wears in properly.

Time for some repairs! Since I’ve owned this forklift it’s had minor leaks in the primary lift cylinder and one of the tilt cylinders. The secondary lift cylinder and the other tilt cylinder were still in good shape. Eventually, the lift cylinder leak developed into a steady drip leaving puddles wherever it was operated and one day the tilt cylinder oil seal blew out altogether. It was time to address the issue.

I had my company mechanic helping me on this job; it’s nice to have a hand on the heavier stuff. Many people are afraid to work on hydraulics, but cylinder repair is actually fairly easy. In fact, most of it is easier than working on motorcycle forks.

I started with the lift cylinder. Given its size, it was easier to disassemble on the machine. We unhooked the lift chains and lines accordingly. We then used a chain wrench to remove the gland nut.

Removing the Gland Nut

Once the gland nut was removed we were able to begin pulling the ram tube.

Removing the Ram

Inspecting the Bore

Once everything is loose, the ram pulls right out and you are ready to install your new packing components. The wiper seal is typically located in the gland nut and the guide bands are usually on the ram.

For the tilt cylinder, we simply removed the whole unit and disassembled it on the bench. It comes apart the same way as the lift cylinder. Once we had the parts pulled we were able to measure for replacement packing.

The lift cylinders are single acting. They power up and load gravity pulls them down. The tilt cylinders are double acting, they power in either direction.

Rather than search for parts online, which is what I usually do and probably what I should have done here, I figured it would be faster to go to the local hydraulic shop although they are typically very expensive. It turns out, the seal used on the lift cylinder was obsolete (or so they told me) and hard to order, so the shop fitted the gland nut with a more common seal diameter by using a lathe to turn the inside of the nut to a larger diameter. The other components were easy to order but unfortunately, the entire process took them about two or three weeks because they apparently had systematic memory failure which inhibited them from placing the order for the seals in a timely fashion. The cost of the parts and labor from the local hydraulic shop (not including hydraulic fluid and the labor on my end) was $198.00. Once I got all my components we had the machine back together within a couple of hours and it was ready to go. I think next time I’ll find the parts myself…cheaper and faster.

Click Here for an UPDATE.

Click Here for more hydraulic repairs.

Cosmetic Restoration

Now it’s on to cosmetics. I wanted the machine to look as good as it runs so I figured it was time to give it the liquid rebuild. From the factory, this forklift was construction yellow with black and orange decals. At some point in it’s life it was painted by a dealer white and black with new decals. Although they did an excellent job, it was now outlived and time for me to restore it. The overall quality of a finished product is directly impacted by the preparation.

It wasn’t my intention to produce a show-quality forklift but I also didn’t want a shade tree job. I planned to use the machine regularly and it would be out in the weather most of the time. With this in mind, I needed a good quality job that would hold up to the weather but not one that would require months of sanding, filling, and priming. I decided to stick with the white and black color scheme. I purchased a gallon of white industrial enamel and a quart of black. The great thing about industrial enamel is its ease of use. It thins with mineral spirits and can be applied with a sprayer or brush depending on the application. The surface doesn’t have to be perfect, but as with anything, the smoother the better.

Preparation

I started by pressure washing the metal to clean any grease or oil from the surface. I then began stripping the old layers of paint with a 4 inch cup brush on a grinder. The brush was coarse, but not so much that it would damage the metal surfaces. I stripped the sheet metal components, such as the engine compartment covers, down to bare metal. The solid steel surfaces, such as the counter weight and mast, received a smoothing over and removal of any rust or loose paint. The cup brush also served well to remove the old vinyl decals. Once the surfaces were appropriately stripped, I washed the unit again to remove the dust. I then primed all the bare metal areas and followed that up with wet sanding.

I don’t have detailed photos portraying each step of the process, but I did manage to snap a few shots of the project.

Beginning the Process

Using the Cup Brush to Strip Paint

Paint and Decals

Now that I had it ready for paint I assembled my gravity feed spray gun. It’s a low cost paint gun I purchased at Harbor Freight out of curiosity. I found that it worked surprisingly well so I decided to use it on this project. I applied 3 coats of paint as evenly as I could across the machine while waiting the appropriate time between coats. A day or so after the paint was dry I began to apply the new decals. While it’s fairly easy to find decals for farm tractors, it is very difficult to find decals for construction/industrial equipment. I was able to find the long “Allis-Chalmers” decals seen along the side and rear on eBay. The rest of the decals were custom made. I took photos and measurements of the old decals and emailed them to a sign shop who was able to reproduce them. They worked perfectly.

Below are some “before” and “after” photos of the forklift.

Before

After

Before

After

Before

After

Before

After

Finished Product

See the Allis-Chalmers ACP80 Lift Truck page for the specs of this machine.