HF 1” Air Impact, low power

[Birdseye]

Holy cow ! I’ll take two !

Those babies probably hold the entire rod length when torquing and not just at the end like I do.

With these huge amounts of torque, during the 1000’s of cycles during operation there must be counterclockwise force that causes or caused that bolt to loosen. That would be annoying and potentially dangerous were that bolt and piston to loosen.

 

[56wrench]

with piston nuts, correct torque and red loctite are your long-term friends. too much torque will stretch the threads and you don't want to be the next guy that has to take it apart. i have been that guy

 

[Birdseye]

Darn , I used blue Loctite!

At what torque does red release it’s grip, does it always require heat to break red Loctite free?

 

[Tinkerer]

Blue Loctite is OK, Birdseye.
Red is to, but ya gotta heat it to at least 500 degrees. I rarely ever used the red stuff.
On a big fine threaded bolt or nut hydraulic cylinders you won't pop red loctite loose without heat.
Unless you have a big a## commercial cylinder bench.

 

[Birdseye]

The backhoe service manual doesn’t go into the details of rebuilding the cylinders so I don’t know what the torque specs are on the rod bolts.

Is it possible that the tightening torque doesn’t have to be more than say 700-800 lbs (150 lbs x 5’ cheater) and let the blue Loctite do the rest. Would you trust that for backhoe type loads and cylinders?

 

[Birdseye]

That’s good to hear about blue Loctite.
The backhoe service manual doesn’t go into the details of repacking cylinders so I don’t actually know what the rod end bolt tightening torque specs are. Is it possible that a moderate amount of torque say 750lbs ( 5’ cheater x 150 lbs) with blue Loctite would be sufficient for backhoe type loads and cylinders?

 

[mitch504]

I would think so

 

[NH575E]

I don't own a tube of red locktite. I always use blue.

Here is a tightening torque chart that might help.

 

[Delmer]

Is it possible that a moderate amount of torque say 750lbs ( 5’ cheater x 150 lbs) with blue Loctite would be sufficient for backhoe type loads and cylinders?

Not in my opinion, find the torque figure and get as close as you can, and use red locktite. Do you WANT to take it apart again? No fun if the nut comes loose, it will make lots of sharp little metal pieces that will travel throughout the hydraulic system, more fun than covid at a hockey game.

 

[DMiller]

Inside a component that is generally run to failure Red Loctite is your friend, it does NOT come loose easily. If you want it back apart on a site, BLUE Loctite ONLY.

 

[John C.]

A phone call to a dealer should get you the torque procedure. Post what machine and which cylinder it is and someone here will likely be able to tell you what you are looking at. In my early years there weren't no cylinder benches or multipliers. It was red Loctite and a big pipe wrench or a slab of plate with a hex hole cut in the center, as that is all there was. You used a pipe on the wrench and a happy tapper on the plate.
When the Japanese excavators showed up on our shores, the benches became a necessity. It needs to be done right. I have personal experience of trying to get an excavator back on a barge with the arm cylinder pulling in all the time and the swing wouldn't quit turning because someone thought a cheater on a big wrench would tighten the arm cylinder rod nut tight enough.

 

[partsandservice]

This may or may not apply. When trying to bust a cylinder loose, if the rod is not completely secured the impact will just transfer the enegy down the rod making it rattle around. When using a pull it will take all the slack out and deliver the enegy to the nut/bolt.

 

[Tinkerer]

Birdseye,
The torque values are in the service manual. I'm posting the page for the dipper cylinder.
Notice it says to use blue Loctite !
Also notice what it says about lining up the set screw.

 

[NH575E]

It's definitely all about the air.

I have been wrestling with the piston bolt on my crowd cylinder. The bolt is about 1-1/4" with an 1-15/16" head.

I began with a 3' pipe wrench and a 10' pipe and it wouldn't budge. I bought the 1" pistol grip impact from HF. $128 with a coupon. I ordered a 1" drive impact socket to fit. I installed the "high volume" air fittings sold at HF which have a 1/4" NPT thread and a 5/16" hole. I put those at every connection on my compressor and have the air running through 100' of 3/8" hose. I knew my compressor was too small but thought I would give it a try first. Nothing doing!

I had to go to the welding supply store to get my oxy acetylene tanks replaced so I took all the stuff with me. He had what looked to be a 5 to 7 HP two stage compressor but it was connected to the standard 3/8" hose with 1/4" fittings. I installed the fitting that came with the gun and hammered on it a while with his air supply and it didn't budge.

I started out towards a hydraulic cylinder repair shop I had never used that didn't answer the phone. Along the way I saw the industrial John Deere dealer so I pulled in and asked if they could get the bolt loose. The guy set my rod in a vise and used my pipe to hold the eye end and my socket on the bolt. He pulled out the EXACT SAME Harbor Freight 1" impact gun I have. He put some oil in it and connected it to what looked to be a 3/4" hose. His fitting must have been a full 3/8" ID because that is the thread in the gun inlet. He spun it free to let the oil circulate then put the socket on. It didn't even hammer! It just spun the bolt out as soon as he pulled the trigger. I wish I would have asked about their air supply other than the large hose and fittings.

This has me wondering if you can get by with 100 PSI as long as you have the first blow volume. My little compressor has a 2" pipe plug in the tank. I wonder if I bushed it down to 3/4" and got the full 3/8" high flow fittings on a 3/4" hose if it would work?

The bolt just had a small spot of BLUE locktite on it. When you think about it these bolts have zero rotational stress. All they have to do is keep the piston stationery while it gets forced back and forth. Yes it has a LOT of force applied but it never turns.

 

[Tinkerer]

Big air tools require a lot of volume and pressure.
Big tank and big hoses.
100 feet of 3/8 hose will never deliver the volume you need. IMHO !
I am aware you already know that but it bears repeating.
150 to 175 psi would be ideal for those big impact wrenches.
You may have a defective HF impact wrench.

 

[colson04]

It's definitely all about the air.

I have been wrestling with the piston bolt on my crowd cylinder. The bolt is about 1-1/4" with an 1-15/16" head.

I began with a 3' pipe wrench and a 10' pipe and it wouldn't budge. I bought the 1" pistol grip impact from HF. $128 with a coupon. I ordered a 1" drive impact socket to fit. I installed the "high volume" air fittings sold at HF which have a 1/4" NPT thread and a 5/16" hole. I put those at every connection on my compressor and have the air running through 100' of 3/8" hose. I knew my compressor was too small but thought I would give it a try first. Nothing doing!

I had to go to the welding supply store to get my oxy acetylene tanks replaced so I took all the stuff with me. He had what looked to be a 5 to 7 HP two stage compressor but it was connected to the standard 3/8" hose with 1/4" fittings. I installed the fitting that came with the gun and hammered on it a while with his air supply and it didn't budge.

I started out towards a hydraulic cylinder repair shop I had never used that didn't answer the phone. Along the way I saw the industrial John Deere dealer so I pulled in and asked if they could get the bolt loose. The guy set my rod in a vise and used my pipe to hold the eye end and my socket on the bolt. He pulled out the EXACT SAME Harbor Freight 1" impact gun I have. He put some oil in it and connected it to what looked to be a 3/4" hose. His fitting must have been a full 3/8" ID because that is the thread in the gun inlet. He spun it free to let the oil circulate then put the socket on. It didn't even hammer! It just spun the bolt out as soon as he pulled the trigger. I wish I would have asked about their air supply other than the large hose and fittings.

This has me wondering if you can get by with 100 PSI as long as you have the first blow volume. My little compressor has a 2" pipe plug in the tank. I wonder if I bushed it down to 3/4" and got the full 3/8" high flow fittings on a 3/4" hose if it would work?

The bolt just had a small spot of BLUE locktite on it. When you think about it these bolts have zero rotational stress. All they have to do is keep the piston stationery while it gets forced back and forth. Yes it has a LOT of force applied but it never turns.

I started doing a bit of searching after reading this thread looking for large air hoses and fittings. For around $100, you can get a 50ft 3/4" jackhammer air hose with universal (Chicago) style fittings crimped on, 2 more Chicago style fittings for gun and air compressor, and the plumbing pieces to mate up to your tank. A bit of threading parts together and you'll never short your 1" impact gun for air because of the hose.

 

[Tinkerer]

I started doing a bit of searching after reading this thread looking for large air hoses and fittings. For around $100, you can get a 50ft 3/4" jackhammer air hose with universal (Chicago) style fittings crimped on, 2 more Chicago style fittings for gun and air compressor, and the plumbing pieces to mate up to your tank. A bit of threading parts together and you'll never short your 1" impact gun for air because of the hose.

Perfect choice !
Safety wire in the Chicago fittings is mandatory.

 

[Swetz]

This is what me employer uses on pneumatic tools used in pipeline installation

https://www.whitecap.com/apt-safety...y7e5DyXQpahoCVhQQAvD_BwE#WTC2001875-20018754/

 

[Delmer]

The size of the compressor tank determines how fast the pressure drops off only. The pressure determines how much force the impact has. The restriction in the hose determines how little pressure the impact actually gets, doesn't matter if you have 175 in the tank, a hose with 3/8 fittings won't have 100 at the gun. The flow is irrelevant, the gun will flow what it will based on the pressure supplied to the gun, if you don't supply the pressure to the gun, you don't get flow or power.

Make sure the threads are perfectly clean before using locktite, it won't do anything with oil.

 

[NH575E]

Big air tools require a lot of volume and pressure.
Big tank and big hoses.
100 feet of 3/8 hose will never deliver the volume you need. IMHO !
I am aware you already know that but it bears repeating.
150 to 175 psi would be ideal for those big impact wrenches.
You may have a defective HF impact wrench.

I wanted to try MY wrench but the fitting I had wouldn't fit their hose. I bet if I would have asked he would have let me switch fittings to test my gun.

Either way I've been getting by with what I have for 30+ years so I will probably take this gun back to HF and forget about it until the next time. I know a place that can loosen bolts for me when I need them.

His supervisor no charged it so I slipped the mechanic a $20 bill.