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| MEC 470: A most satisfying "ponk" http://www.rypn.org/forums/viewtopic.php?f=1&t=43103 |
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| Author: | Richard Glueck [ Sat Mar 02, 2019 7:38 pm ] |
| Post subject: | MEC 470: A most satisfying "ponk" |
An old school tool, was machined by CMO Leverett Fernald to separate the tapered pistons from the crossheads on Maine Central 470. Combinations of heat and lubrication, hydraulic jacks, more heat, just didn't do the job. Finally the proper tool was suggested and it worked beautifully. Maybe the people who worked in steam shops for the major railroads just might have learned something? Leverett is a machinist by trade and used old drawings to create this set. That's him with the sledge hammer. When the pistons let go, there was a most satisfying "ponk" noise. Big surprise was how clean everything was around the tapered fitting. We expected years of corrosion, and found the surface clean as a whistle. These had not been apart for over 70 years. https://drive.google.com/file/d/17TW_A1 ... sp=sharing https://drive.google.com/file/d/1KOu8it ... sp=sharing https://drive.google.com/file/d/12eKmzy ... sp=sharing https://drive.google.com/file/d/1fNAWF8 ... sp=sharing https://drive.google.com/file/d/1zJUqMR ... sp=sharing https://drive.google.com/file/d/1bsdsHF ... sp=sharing https://drive.google.com/file/d/18E1N0k ... sp=sharing |
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| Author: | Rick Rowlands [ Sat Mar 02, 2019 8:13 pm ] |
| Post subject: | Re: MEC 470: A most satisfying "ponk" |
I have seen illustrations of those tools but until now have not seen one. Great going! |
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| Author: | Aarne H. Frobom [ Sat Mar 02, 2019 8:35 pm ] |
| Post subject: | Re: MEC 470: A most satisfying "ponk" |
In the earliest days of our work with Pere Marquette 1225, the former Wyoming roundhouse foreman appeared at MSU with a steel box containing the hydraulic-powered version of this tool. It had been squirreled away for years following the departure of the last steam engine. It is a cylindrical device that replaces the wristpin, and drives a wedge against the end of the piston rod under many thousand pounds of pressure. Works great. It's always been fascinating to me that the power of each piston is transmitted by the taper, acting in tension half the time, and held only by friction. Aarne Frobom |
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| Author: | Dennis Daugherty [ Sat Mar 02, 2019 10:15 pm ] |
| Post subject: | Re: MEC 470: A most satisfying "ponk" |
The tool Aarne is describing is a Sperry Hydraulic piston rod parting tool. I have the operating manual for one. They were sold in two sizes. The larger was 250 ton capacity the smaller 150 tons using 30,000PSI hydraulic pressure. With those capacities it shows the forces requires to break the tapered fit of piston rod into crosshead. The tool 470 people made is a excellent style and the simplest to make but needs made from alloy steel then heat treated as they will deform under the intense loads required to part a piston rod Also various styles were made using a false wrist pin with either a screw or wedge design to apply the force onto the end of the piston rod. Dennis Daugherty |
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| Author: | 10stewi [ Sun Mar 03, 2019 9:02 am ] |
| Post subject: | Re: MEC 470: A most satisfying "ponk" |
I would very strongly emphasize Dennis's words! I made a set in 2015 that copied an earlier set, and didn't harden them. It did the job, but oh man were the parts bent and unusable after the job was done! -wanted to attach some photos, but apparently the "board attachment quota" has been reached |
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