Jump to content

Fixing an H3PR tube bender


Recommended Posts

My tube bender wont hold pressure when trying to bend tube so I decided to try and repair it.

First prepare your work area - cleanliness is the order of the day


Here's the machine, holds less fluid than a seive... :(


and here are the replacement seals and O rings


First we take the top off the reservoir by removing the six cap head screws


Once the bolts are out the top simply lifts off. Put the gasket in a safe place.



Remove the plunger and return spring and put them to one side for now


Once you have drained the oil secure the ram in the vice as the next job is getting the end cap off. I had to encourage it with a bit of heat, but don't get carried away as there is a rubber seal betwen the cap and the end of the ram housing. Anyhow, a bit of heat and some brute force with a chain wrench and it came off. Don't loose the sealing ring from inside the cap.....



The ram will now withdraw although it does need some encouragement from the other end ;).

Post 2 to follow.......

Link to comment
Share on other sites

Here's the ram on the bench with the suspect seals at the right hand end


The seals are held on with a nut and washer and it is done up extremely tight.


To undo this, I put the nut in the vice and then used my longest 3/8" extension through the hole in the other end of the ram. More grunting and swearing and it gave in :)


Once the nut and washer are off, the seals and spacer block will slide off the end of the ram. There is an o ring on the shaft so they might need a bit of help. Here are the three bits on the bench


and the end of the ram with the o ring


The seals are a press fit onto top hat spacers. Mine separated by hand (just).

Refitting is the reverse of removal, to quote the book of lies. The new seals will need to be guided in to the end of the ram. I did this by standing the ram on end and using a blunt screwdriver to ease the seal into the body of the ram. Be sure to lubricate the new seals with some fresh oil before you put them in.

Next I turned my attention to the plunger as the seal on the end of that had seen better days


A quick turn of an alen key saw that seal replaced, lubed and back in position with the return spring.

The last seal I replaced was the O ring that should seal the reservoir from the handle piston. My seal wasn't and results in oil all over the place. I took the handle off to give me some room - just remove the C clip and withdraw the pin. You can then push the piston out



The O ring sits in the bore of the piston and is easiliy picked out and replaced. Again, remember to lube it before installing it.

So, after all that you can put the piston back in, the handle back on, refit the top of the reservoir with gasket and refill with oil. Obviously, the ram will have lots of air in so you need to bleed it by pumping in and out :ph34r: repeatedly. Be sure to monitor the oil level to stop air being drawn in. Ensure the breather on the top of the reservoir is cracked open whilst pumping or you will wreck your new seals.

So, did it work? Oh yes :i-m_so_happy::i-m_so_happy::i-m_so_happy:


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy