lebenfitz Posted October 8, 2020 Share Posted October 8, 2020 Hello! I'm wondering if anyone would be able to answer a question for me in regards to cwt. I'm currently working on a project for the South Eveleigh Locomotive Workshops down here in Australia, which was once the heart of Australia's second industrial revolution and where several hundred trains were built over the course of 100+ years. There's a number of steam hammers and presses that remain, one of which is still used in a functioning blacksmith's shop. It's a 40 cwt double arch steam hammer (since this is British imperial that makes our cwt = 112 lbs), and simply put I've been trying to understand if there's a way to calculate the force of the machine's blow. And also how to compare this to say the force of a manual hammer blow onto an anvil. My understanding is that 40 cwt refers to the weight of the ram - but not the force of the blow. I've read references about double arch hammers having a '125 ton blow' for example. Thanks to anyone who can shed any light on this for me, it's very much appreciated! Quote Link to comment Share on other sites More sharing options...
George Geist Posted October 8, 2020 Share Posted October 8, 2020 Before Mr Powers gets here with all the answers I'm not sure if I'm understanding the question. Normally those type of machines whether they be steam, air or mechanical are variable speed and hitting force depending on how much pressure you apply to the foot pedal or other operating device. Are you wanting to know how much force it's capable of at full force? If so I'd guess it just depends. In addition to ram weight the steam or air pressure would need to be known as well. George Quote Link to comment Share on other sites More sharing options...
lebenfitz Posted October 8, 2020 Author Share Posted October 8, 2020 Hi George - yes that's correct, I'm really just after an estimate of it's full force. As far as I know the steam pressure at the site was limited to 100psi - so is that enough info for a ballpark calculation? Thanks for your reply! Quote Link to comment Share on other sites More sharing options...
George N. M. Posted October 8, 2020 Share Posted October 8, 2020 It would depend of whether the ram is simply raised and released and allowed to fall by gravity or whether there is an added downward force added by steam, air, flywheel, etc.. If the former you can use your old High school physics to calculate the speed with which the ram is moving when it falls X distance and convert that to force or work. If the latter you will have to know more about air or steam pressure or the mass and velocity of a flywheel and how efficiently that force is added to the ram. "By hammer and hand all arts do stand." PS The pressure is only one variable. The diameter of the piston minus friction would be the other main variables. The other George Quote Link to comment Share on other sites More sharing options...
JHCC Posted October 8, 2020 Share Posted October 8, 2020 To expand on the other George's last remark, the ram will move with a force of the cross-section of the piston multiplied by the pressure. Consider two pistons, one with a 10" diameter and the other with a 20" diameter. The first will have a cross sectional area of 25pi square inches; multiplied by 100 psi gives approximately 7,900 pounds of force, which is 3.95 short tons. The second will have an area of 100pi square inches; multiplied by 100 psi gives about 31,400 pounds of force, which is 15.7 short tons. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 8, 2020 Share Posted October 8, 2020 Factoring in steam expansion might be tricky. I know that hammers converted from steam to compressed air lose some oomph. Quote Link to comment Share on other sites More sharing options...
Frosty Posted October 12, 2020 Share Posted October 12, 2020 Steam pressure increases when the pressure first lowers. So as the piston first begins to move the wet steam in the cylinder flashes to dry steam and the pressure shoots up. If you've ever opened the radiator cap on an overheated engine and had it immediately boil over you've experienced what I'm talking about. Compressed air does the opposite as the volume it occupies increases the pressure goes down. 2x the volume 1/2 the psi. Sometimes in old steam powered equipment locking or wiring the pressure relief valves / whistles was to prevent the pressure drop and prevent a steam explosion. Another B A D mistake caused the Sultana boiler explosion. The wreck is still in the river and a few years ago it was examined and analyzed for the real cause. Eye witnesses and survivor accounts were too varied. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
JHCC Posted October 12, 2020 Share Posted October 12, 2020 I can barely imagine what it must have been like to survive Andersonville only to get blown up with the Sultana. Quote Link to comment Share on other sites More sharing options...
SLAG Posted October 12, 2020 Share Posted October 12, 2020 John, It was a moving experience. SLAG. Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted October 20, 2020 Share Posted October 20, 2020 On 10/7/2020 at 8:56 PM, lebenfitz said: I'm wondering if anyone would be able to answer a question for me in regards to cwt. Grand looking machines, are they running on steam or converted to air? There does not appear to be any lagging on the delivery pipes... Best bet would be to ask John Nicholson of Massey in UK. http://www.masseyforging.com/home.htm The pressure of steam or air acting on the diameter of the piston are the starting point, but only give you the same result as for a hydraulic press. Crucially the length of stroke it accelerates through will have the greatest effect on the effectiveness of the hammer. Perhaps next best bet is to look at the Massey hammer brochure which shows that the 40CWT Clear Space Air Hammer generates a blow energy of 6,400kgm Hope that helps, Alan Quote Link to comment Share on other sites More sharing options...
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