Thought this might be interesting to some of you. We rebuild a lot of hammers and presses at my company - This is a photo montage of a 2500 ton ram and pitman we overhauled last month.

The assembly weighs about 16 ton all up. The clearance on the bronze bush to the crankshaft is 0.016" max when done! The bolts are shrunk in place with heating elements to give the correct pre-tension.

All the surfaces have to be in 'bed' contact or the assembly will not last very long in service! you can see we extensively use chalk and blue to check contact in some of the photos.

The bearings you can see being removed at the start of the video have been in about 5 years, you can see where they have melted and extruded!

Towards the end of the montage there is a video of the bearings being hand scraped - The guy has been doing them for 40 years - makes it look very easy! We scrape the bearings to give an extra couple of thou clearance at the sides, which aids the oil flow to the point that does the work under a full forging load.

The complete press weighs about 250 tons, and is used for hot forging automotive components, cylces about once a second! Ill try and dig out some photos of the full machine.

http://www.youtube.com/watch?v=dzx-NbS20Pk

Very cool, share more stuff like this if you get a chance!

Amazing machine skills there John, I love the big stuff :rolleyes:

This is a clutch from a different 2500 tonner we did last year, real headscratchers to get right these! 24 drive bolts all have to be in contact with 24 slots!

http://www.youtube.com/watch?v=uiRuig6EDvo&feature=plcp