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Cleveland worm gearing was first manufactured in 1912. At that time worm gearing was used primarily by the automotive industry for rear axle drives. Within a few years its application for industrial needs assumed major importance, and in 1918 the country's first standardized line of worm gear speed reducers was introduced under the name of "Cleveland." Many units built during those early years are still in service.

By specializing in the manufacture of worm gearing, and through a contiguous program of research and development, the name "Cleveland" has steadily maintained leadership in industry. Because of this policy of specialization, many advances have been pioneered in mechanical power transmission that have been of fundamental value to industry.

In its manufacturing processes, Cleveland has recognized from the beginning that no one worm thread form is superior to all others. It began with a basic form that was and is the easiest and least costly to produce, and proceeded to refine it to provide the best possible tooth contact. True conjugate action between the worm thread and gear tooth is of prime importance in worm gearing, and efforts have there fore been to improve the contact by strict adherence to closer and closer manufacturing tolerances.

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From its beginning Cleveland has specialized in the manufacture of worm gearing. Its shop equipment has been designed exclusively for such manufacture, providing the means to produce industrial coarse pitch worm gearing of the highest quality. 1920
	Today Here is a brief discussion of some of the more important techniques used in its manufacture.
HEAT TREATING Cleveland flame hardens all worms in its fan-cooled line and can flame harden worms up to 56.000" gear centers. After milling, worms are mounted on a spindle of the Flamatic machine and rotated in an oxyacetylene flame, then automatically quenched in an oil bath. Time and heat conditions determined by worm size are rigidly controlled. Flame-hardened heat treatment gives the worm a high degree of hardness throughout the entire thread thickness (55-60 Rockwell "C" on the surface) to well below the root diameter, yet retains a core of medium hardness.
	THEAD GRINDING Cleveland worms are machined either from bar stock or forgings. After rough turning, milling and heat treating operations, both worm thread flanks are ground at the same time,there by minimizing errors. Two grinding wheels are used; first-a rough grit type removes metal to within a few ten thousandths of the final desired dimension. A fine grit wheel is then used, giving threads the mirrored surface desirable in worm gearing. Because of the importance of this operation, specially designed precision thread grinders, are used that are constantly maintained at a high degree of accuracy.
HOBBING Cleveland worm gears are hobbed by the "tangential feed" process on specially constructed machines designed to overcome certain short- comings inherent in other methods, such as fly cutting and radial hobbing. The tangential feed hobbing process employs a hob made up of two elements called the "rougher" and "finisher". The roughing portion of the hob is fed gradually into the gear blank first to remove metal from the gear tooth spaces. Next, the finishing portion moves tangentially through these spaces and generates the proper profile on the gear teeth. In this phase of the hobbing operation each rotation of the hob is accompanied by a slight feed movement tangential to the gear and has the effect of progressively creating a new series of cutting edges, by relocating them with respect to the gear. The gear tooth is therefore generated by an immense number of different cuts that result in an almost perfect contour in the finished tooth. This smooth tooth profile is an important factor in a gear's load carrying ability, smoothness of operation and efficiency.
	INSPECTION Cleveland maintains an inventory of more than 1500 hobs and master worms. Master worms constitute a permanent job record, which assure an accurate duplication of every worm and gear ever manufactured by Cleveland. Regular inspections of production worms are made in an air-conditioned inspection room. Here a production worm is checked against its corresponding master worm. Its thread contour is compared to the master's, and any deviation is recorded in tenths at specified intervals above and below the pitch line. The worm thread's lead, index and variation from uniformity are measured in tenths and recorded. This also provides a check on the thread grinder's performance. Slight deviations from perfection are recorded, and if they reoccur, it is possible to positively identify that part of the thread grinder responsible and correct it before the variation exceeds the permissible. Special gear checking machines are employed to verify accuracy of the hobbing operation. A hobbed gear is mounted in the required dimensional relationship with a mating worm or master worm, so that contact can be verified, together with resulting backlash. All gear checking machine settings may be quickly and accurately checked by gauge bars which insure accuracy of the work and prevent deviation from standard size.

 

1-800-423-3169
Cleveland Gear Company
3249 East 80th Street
Cleveland, Ohio 44104
sales@clevelandgear.com

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