It seems I garbled part of one of the sentences below. The catch wings are mounted above the beam in such a way as to stop the piston passing through either the bottom or (sometimes) top of the cylinder. It is, of course, physically connected to the beam rather than as my previous sentence might have inferred being separate from it. Interestingly, I was once at Kew Bridge when their 90 inch engine came indoors at such a rate that the catch-wing caught the spring beams fairly spectacularly. The whole engine house seemed to be rattled. Re the comments about Cruquius, it strikes me that with that engine the beams were mounted radially around the engine house so now I'll have to look at my old photos to try and decide how the protection was arranged on that machine :-) Lastly, on the subject of controlling Cornish engines, there was another component employed to control the time the engine paused at one, or sometimes both ends of its stroke. This was in the form of a cataract device that using a small tank of water and a float was attached to the valve gear to inhibit release of the appropriate quadrant for a period of time. Typically these were employed to pause the engine at the end of its out-door stroke to give sufficient time for the pump valves to close before going indoors again. Not all engines had these devices but they were quite common, if not always obvious as they were often hidden away in the 'cockpit' below the engine room floor. During the nineteenth century there was considerable discussion from the 1860s onwards as to the suitability of Cornish engines for waterworks service. Some of this material is likely to be reproduced along with the article on the Sims engine at Crofton in a forthcoming edition of the ISSES annual journal Stationary Power. Paul Stephens IT Manager DS Smith Corrugated Bristol Tel. 01275-551023 (Direct) Tel. 01275-375311 (Switchboard) Fax. 01275-374939 Mob. 0787-644-6777 -----Original Message----- From: Paul Stephens Sent: 08 September 2003 13:48 Subject: Re: Spring beams The devices designed to stop a non-rotative beam engine from destroying itself seem to go back almost to the earliest days of the beam engine. The two components that normally appear on these engines were the catch wing, mounted above the beam with a fixed above the beam, usually to a pin pretty much in line with the centre line of the piston rod. The spring beams were made of large baulks of timber designed to stop the engine coming too far in-doors and smashing the bottom out of the cylinder. Generally, but not always, a similar arrangement was provided on the outdoors (pump end) end of the beam to stop the piston coming through the top of the cylinder, or damage to the pumps. Usually a replaceable piece of timber was attached to the top of the spring beam to take the brunt of the strike from the catch wing. Sometimes India-rubber was used instead as can be seen on at least one of the engines at Crofton. Close examination of most of the surviving non-rotative engines will show marks indicating that the spring beams would e stuck fairly often. This would occur either during starting when the engine would be worked by hand, or during a mechanical failure when something broke. In some cases additional equipment was added to the plug-rod operated valve gear to provide additional means of stopping the engine should a over-stroke occur. Paul Stephens IT Manager David S Smith Corrugated Bristol David S Smith Corrugated Bristol First Avenue, Portbury Way, Portbury, Bristol, BS20 7XR Tel: +44 (0) 1275 551023 (Direct) +44 (0) 1275 375311 (Switchboard) Fax: +44 (0) 1275 374939 -----Original Message----- From: Newman, Phil [mailto:[log in to unmask]] Sent: Monday, September 01, 2003 08:57 Subject: Re: Spring beams Thanks Andrew, now I understand what they're for but where exactly were the cross arms or arch heads located? Were they fixed to the beam? On the famous Perran Foundry cross section for example (printed in Barton and elsewhere) the cylinder end of the beam on the in-house stroke is below the top of the spring beam. Is the cross arm not shown on this drawing? Thanks for your help Phil Newman -----Original Message----- From: Andrew Hurrell [mailto:[log in to unmask]] Sent: Friday, August 29, 2003 6:54 PM To: [log in to unmask] Subject: Re: Spring beams The spring beams on a non-rotary beam engine are there to act as a buffer. If the engine hits the bottom of the cylinder on the 'in-house' stroke or the top of the cylinder (and bottom of the pumps) on the 'Out of House' stroke there is a good chance that the engine will smash the cylinder casting. This could be because of something like a pump rod breaking or the valve gear not operating properly. Cross arms ('Arch Heads' ?) raised above the ends of the beams line up with the spring beams. When the engine is working correctly, the arch heads should stop just short of the spring beams. The Dorothea engine, because the pump rods are missing, is sat on the spring beams inside the engine house. The beams in this case start under the bearings and can clearly be seen to be smaller than the structural beams below. Regards Andrew ----- Original Message ----- From: "Newman, Phil" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, August 29, 2003 11:10 AM Subject: Spring beams > Dear list, > > Could someone please provide a concise definition of a Spring Beam. Most > diagrams of engine houses in the usual sources show them and the sockets are > usually quite evident in the structures but there precise function is not > fully clear to me. > > Thanks in anticipation > > Phil Newman > This e-mail is intended solely for the person to whom it is addressed and may contain confidential or privileged information. If you have received in error please notify us immediately and destroy this e-mail and any attachments. In addition you must not disclose, copy, distribute or take any action in reliance on this e-mail or any attachments. 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