Steam engine piston rings

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General

Pistons are describe in detail at http://en.wikipedia.org/wiki/Piston. The seal against the cylinder wall is formed by one or more piston rings.

Piston rings need to be cut so that they can slide over the piston into a machined groove. Cast iron rings are brittle, so care must be taken when fitting them. Cuts come in several types:

• Step Cut - common for noncritical sealing applications
• Butt Cut - common where high leakage rates are permitted
• Hook Cut - used in transmissions (etc) where oil passage may be needed.
• Angle Cut - used in rotating seals. Restricts bypass in the joint.
• Angle Step - injection moulding.
• Step Seal - a step cut with in inner seal.
• Two Ring Set - butt cut inner and a step but outer ring. Good for high temps and high pressure seals.
• Three Ring Set - 1 butt cut inner and two butt cut outers (staggered).

Other features of piston rings include:

• Chamfer
• Radius
• Scraper
• Vent
• Groove
• Bronze Insert
• Taper

Cast iron rings are used because they are low-friction and resist wear. The mechanical structure of cast iron produces consistent pressure against the bore (cylinder walls).

Manufacturing Description

At Federal-Mogul grey iron piston rings are cast as individual rings in a noncircular shape; there are other ring manufacturers who cut the individual rings from pots or cuffs. The rings are generally machined to the required shape by means of double cam turning, a process in which the ring blank, already axially ground, is copy turned simultaneously on the inside and outside diameters. After a segment equivalent to the free gap is cut from the ring it assumes the free shape that will give it the required radial pressure distribution when fitted into the cylinder. Once inside the cylinder the ring is completely light tight on its outside diameter and exerts the predefined radial pressure against the cylinder wall.

Besides using double cam turning, ring blanks can also be shaped by machining the inside and outside diameters separately. This involves cam turning the outside diameter of the noncircular blank and machining the inside diameter with the ring in the compressed state. The gap is cut out in a step between O.D. and I.D. machining. Heat forming as a means of shaping piston rings should be mentioned to complete the range of options, but this process is seldom used.

Steel piston rings are made from a profiled wire. The rings are first coiled into a circular shape and then the gap is cut out. The necessary shape is obtained using a heat treatment process in which the rings are mounted onto an arbor appropriately designed to impart the required radial pressure distribution.

Profiling of the running faces of taper faced, Napier and slotted oil rings is carried out, depending on the ring design, on automatic O.D. lathes or profile grinding machines using special profile cutting tools before or after coating.

ISO Standards for Piston Rings

(From Federal Mogul)

ISO - Desig. Edition Title ISO 6621-1 11 / 2007 Vocabulary ISO 6621-2 11 / 2003 Inspection measuring principles ISO 6621-3 09 / 2000 Material specifications ISO 6621-4 10 / 2003 General specifications ISO 6621-5 12 / 2005 Quality requirements ISO 6622-1 12 / 2003 Rectangular rings made of cast iron ISO 6622-1 10 / 2003 Rectangular rings made of steel ISO 6623 02 / 2004 Scraper rings made of cast iron ISO 6624-1 08 / 2001 Keystone rings made of cast iron ISO 6624-2 10 / 2003 Half keystone rings made of cast iron ISO 6624-3 08 / 2001 Keystone rings made of steel ISO 6624-4 10 / 2003 Half keystone rings made of steel ISO 6625 12 / 1986 Oil control rings ISO 6626 07 / 1989 Coil spring loaded oil control rings ISO 6626-2 10 / 2004 Coil spring loaded oil control rings of narrow width made of cast iron ISO 6626-3 neu Coil spring loaded oil control rings made of steel ISO 6627 09 / 2000 Expander / segment oil control rings

Piston Ring Sources

EPM

Web: www.epm.com/hydraulic_castiron.htm Phone: (800) 659-5050 FAX: (888) 353-7325

Called and had a short discussion. 50 pc minimum less than 1O" bores. Cross section width?

Grover Corporation

Adr: P.O. Box 340080 | 2759 South 28th Street | Milwaukee, WI 53234-0080 Phone: Phone: (800) 776-3602 Fax: (888) 384-6953

Quote request on 4/19/11 by email.

HSC - Hydraulic Supply Co.

Web: www.hydraulic-supply.com Web: www.hydraulic-supply.com/pdf/735.pdf Phone: 1-800-507-9651

Pt.No. Model O.D Width Thickness Weight C1DK98 SPR-4000 4.000 0.248 0.249 0.127/0.142 0.01 C1DK99 SPR-4002 4.000 0.186 0.187 0.127/0.142 0.01 C1DL12 SPR-6004 6.000 0.310 0.311 0.191/0.206 0.15 C1GG42 SPR-7002 7.000 0.248 0.249 0.228/0.243 0.32

Note that they do not have 3" OD rings.

HiTech Seals, Inc.

Web: www.hi-techseals.com Web: www.hi-techseals.com/pdfs/sections/IPC2011_Piston_Seals.pdf - See pg. 98 for cast iron. Loc: Newmarket, ON, CA (other locations in Canada) Phone: 905-953-9666 FAX: 905-953-8739

CI-3000 is a 3" ring. It is a Step Seal joint.

Quote request on 4/19/11.

CECO

Web: TRYCECO.com/Contact Email: TRYCECO@ceconet.com Phone: 800.879.2326

Quote requested on 4/19/11.

Safety Seal Ring Company

Web: www.sswesco.com Web: www.sswesco.com/ss/sspow.htm Adr: 10736 South Pipeline, Hurst, TX 76053 Phone: (903) 938-9241 Phone: 1-800-525-0143 (U.S.A.) Phone: 1-800-962-3631 (International) FAX: (903) 938-0145 (Accounting) FAX: (903) 938-9317 (Sales) After Hours & Weekends: (903)938-0849 Email: wesco@sswesco.com

Plain compression ring, Type PCS Step Cut.

SAFETY SEAL uses a Class 40 Gray Iron which is a more widely used material for piston rings and seal rings. The presence of Type "A" Graphite in a Ferritic or Pearlitic Matrix provides good dimensional stability, uniform hardness, good wear resistance and lubrication retention. The lubrication retention properties of the iron permits the material to be used un-plated and even where lubrication is borderline. This material is also used as a base for plating, IE. Chrome Tin.

Quote requested on 4/19/11. Response: We do not manufacture rings smaller than 7" o.d.. Thank you for the inquiry. Don Seals

Parker Hannifin Corp.

Web: www.parkerseals.com Web: http://www.darcoid.com/images/uploads/pdfs/EPS5301.pdf Adr: Salt Lake City, Utah 84119 USA Phone: (801) 972-3000 Fax: (801) 973-4019

These piston rings seem to require an O-ring as an inner ring.

Federal Fluid Power

Web: http://www.federalfp.com/hydraulic_cylinders.php Adr: 1145 Starkweather, Plymouth, MI, 48170 Phone: 734.455.1722 Fax: 734.455.0222

Hydraulic cylinders - don't seem to make parts available.

Phonenix Piston Rings

Web: http://www.phoenixpistonrings.com.au/products Adr: 51 Cambro Road, Clayton Nth, Victoria. 3168. Australia Phone: 61 3 9544 9169 Mobile: 0403 348 388 Fax: 61 3 9543 1030

Good illustrations of ring types and joints.

Compressor Valves and Plates Services

Web: http://www.compressorsparesworld.com/index.php?page=piston_ring Web: http://www.compressorspareparts.co.in/ Adr: P-20 Phase III, Kasba Industrial Estate, Kolkata-700107,India. Phone: +9133-24429938, 22278137 Mob: +919748086804 Email: compspare@gmail.com, comparts@vsnl.com

Cast iron rings are mentioned, but no details. Prices might be better in India - who knows?

Federal Mogul

Web: www.federalmogul.com Adr: Bürgermeister-Schmidt-Straße 17, 51399 Burscheid, Germany Phone: +49 21 74 / 69 - 0 Fax: +49 21 74 / 69 - 14 90 Email: info.GOETZE@federalmogul.com

Excellent manual that gives background information on nomenclature, custom ring manufacturer. piston ring functions, various forces and stress, ring types, how rings fail, etc.

Precision Rings Inc.

Web: http://www.precisionrings.com/rings.html Adr: 5611 Progress Road, Indianapolis, Indiana 46241 Phone: 317-247-4786 Fax: 317-248-9781 Email: prisales@precisionrings.com

Provide custom ring manufacturing. Quote requested on 4/19/11.

Summit Racing Equipment

Web: http://www.summitracing.com/search/Department/Engines-Components/Part-Type/Piston-Rings/?Ns=Rank%7CAsc&autoview=ProductName&gclid=CMOF4pr_pqgCFRG4Kgodyy-3Hg Adr: P.O. Box 909, Akron, OH 44398-6177 Phone: 800-230-3030 Fax: 330-630-5568

OD generally seem to be 4" or more probably due to racing engine requirements. Prices are in the $25 to $90 range (each).

Making Piston Rings

Andrews Engineering

YouTube videos: www.youtube.com/watch?v=pNoviQVzDDI

How to Make a Piston Ring

modelenginenews.org/techniques/piston_rings.html This site mentions steam engines.

Pistons and Rings

http://www.5bears.com/pistons.htm This technique shows how to cut them on a lathe.

How To Make Your Own Quality Piston Rings

http://www.jerry-howell.com/PistonRings.html Also turned on a lathe.

Making Piston Rings

http://www.neme-s.org/Model_Engineer_Files/3135-Making%20Piston%20Rings.pdf Four techniques are explained. Short, one page article.

Home Metal Shop Club

http://www.homemetalshopclub.org/news/jul03/jul03.html Four methods are described all based on lathe turning.

Piston Rings - The Mystery Revealed

http://www.oldengine.org/members/holland/images/PistonRings/pstnrng1.jpg http://www.oldengine.org/members/holland/images/PistonRings/pstnrng2.jpg

Home Model Engine Machinist

http://www.homemodelenginemachinist.com/index.php?topic=11344.0 These are forum entries discussing how to make piston rings.