Camshafts for Industrial Engines
Camshafts for industrial engines can be one-piece integral camshafts, lobes assembled in many ways onto a shaft, or sectional camshafts.
Integral or one-piece camshafts
One-piece camshafts are manufactured from a single piece of material, either an iron casting or piece of steel bar stock.
A casting is made with oversized lobes and mains which are later ground down to the correct shape and size.
If the cam is made from bar stock, the raw material is turned on a lathe so that the material is removed between lobes and mains,
then the lobe shapes are milled onto the blank. At this point in the manufacturing process, the steel is hardened.
If the camshaft is manufactured from high-carbon steel, induction hardening is used.
If it is made of low-carbon steel, the camshaft is case-hardened by carburization.
The final stage in manufacturing a camshaft is grinding and polishing the lobes and mains.
("One piece" camshafts may have some features which are shrink fit onto them or may be constructed of two pieces joined in the middle.)
Many industrial engines use this type of cam, including Waukesha, Caterpillar, Arrow, Gemini, Moline, and more.
Composite or assembled camshafts
The second type of cam has many variations, all consisting of lobes mounted on a shaft.
This type of camshaft is usually used for larger engines because it is easier to manufacture in large sizes.
The shaft used is typically a plain hardened steel bar that has been ground to a precise diameter, and may have some work done to the ends to facilitate the mounting of gears, couplers, etc.
Shrink Fit Cam Lobe - with Keyway
Lobes are manufactured with an interference fit, and have a keyway to locate them radially for correct timing.
Engines using this arrangement inclue White Superior, Clark, and many more.
Shrink Fit Cam Lobe - without Keyway
These lobes also have a press fit, but they can be moved linearly and/or re-timed during engine maintenance or overhaul by pressurizing them with hydraulic fluid through a port and internal passageway. Industrial engines using this kind of cam lobes include the Cooper LSVB, Enterprise, Delaval, and Nordberg.
Split Cam Lobe
A "split" cam lobe is manufactured as two halves that fit precisely together and are secured with high-grade bolts.
Generally these are indended for use as replacements for an individual failed lobe on a shaft, since they can be replaced without removing the cam shaft from the engine.
However, the Cooper-Bessemer GMV gas compressors use split lobes for fuel injection.
This application is a bit unusual since the GMV is a two-stroke engine, the split lobe does not have a keyway, and the lobes are mounted directly to the crankshaft.
Adjustable Cam Lobe
There are a few examples of cam lobes that are designed to be adjustable radially.
These generally have a flanged hub that is shrink fitted to the shaft.
The cam lobe is a slip fit on the hub, and is held in position between the flange and a ring which is bolted to it.
The cam lobe may be split, to allow substitution of a different cam profile.
Slip Fit Cam Lobe
Instead of having an ID slightly smaller than the shaft, these cam lobes are a slip fit on the shaft. They are held in place with tapered keys. The Cooper Bessemer LSV engine uses this type of cam.
A cam muff is a single piece with several lobes on it. One cam muff may have lobes for one or two cylinders. The cam muffs are also a slip fit on the shaft, and are attached with bolts and threaded tapered pins.
The Ingersoll Rand KVG, KVS, SVG, and a few other models use this camshaft arrangement.
The third type of industrial camshaft is comprised of sections which are bolted together.
These usually have an alignment feature, such as a dowel pin, to ensure that the correct angular orientation of the cams is maintained.
There may be "connecting" shaft sections bolted between each cam section, or they may simply bolt directly to each other.
Industrial engines using this type of cam include the Waukesha AT series and the Ingersoll Rand KVR and KVT gas compressors.
Camshaft and Industrial Engine Links:
Camshaft manufacturing & repair for industrial engines
Waukesha Engine Co.
Caterpillar Industrial Engines
Arrow Engine Company
Camshaft page at Wikipedia
How Stuff Works - Camshaft