Wherever applicable, British as well as Indian standards are used. Worm conforms to case hardening alloy steel, worm wheel conforms to phosphor-bronze PB2-C as per British Standard B.S. 1400, while gear case conforms to C.I. grade FG 220 and for heavy duty FG 250, Indian standard I.S. 210.

Gear case is of streamline design, rugged in construction, made of close grain cast iron. It is completely oil-tight, dust proof and capable of being installed in the open without a separate cover. The face and bore are accurately bored and machined on latest precision machines to ensure perfect alignment and interchangeability.

The worm is made of case hardening alloy steel, carburised, ground and polished and is integral with the shaft. Bearing journal are accurately ground. Worm wheel is made of centrifugally cast phosphor-bronze rims, shrink fitted and brazed with C.I centers. Worms are generated on special purpose worm milling machine machines. Gas carburised and ground on automatic work grinders.

Worm wheel are hobbed on precision hobbing machine with high accuracy hubs. Each and every wheel is checked to match with the master worms to ensure complete interchangeability.

The worm and worm wheel are supported on ball or roller anti friction bearings of ample margin of safety to allow adequate journal as well as thrust loads. Overhang loads arising out of sprocket Or pinion drive are generally permissible because the gear case and bearing are designed for this duty. However, complete details should be given to us for confirmation. In case of heavy overhang loads, as extra roller bearing can be provided.

The wheel shaft are made of high tensile carbon steel. It is of larger diameter to carry the torsional as well as bending loads which may be induced by overhang drives.

Lubrication to gears and bearings is by splash of oil from the sump. No special care is required except for the occasional topping up of oil to the required level. A large oil filter-cum- breather and inspection cover is provided together with the drain plug and ventilator. Neoprene lip-type oil seals are fitted on input and output shaft.

For very low input speed below 50 rpm. And heavy loads in size larger than 14" size forced lubrication is required. In such case Crescent must be consulted.

Air-cooling is effected by means of standard poly-propylene or metal fans which direct a continuous flow of air over the ribbed surface of the gear unit. The fan is designed to operate in both direction of rotation, and is so arranged in conjunction with the ribbing on the gear unit as to allow maximum heat dissipation.

Crescent Sprag type hold back can be fitted on all sizes of gears to prevent reverse rotation. In case where hold-back is required, the direction of rotation of the shaft should be mentioned.