Worm gear

Fluid-pressure distribution tends to close the valve. For this reason, the smaller manually operated valves have a latching device on the handle, and the larger manually operated valves use worm gearing on the stem. This hydraulic unb ance is proportional to the pressure drop and, with line velocities exceeding 7.6 m/s (25 ft/s), is the principal component in the torque required to operate the valves. Compared with other valves for low-pressure drops, these valves can be operated by smaller hydrauhc cylinders. In this service butterfly valves with insert bodies for bolting between existing flanges with bolts that... 

Self Wiping vocuumtight dischorge valve worm-gear-operated... 

Top entering mixers are heavy duty equipment. They are usually fixed to a rigid structure or tank mounting. Either radial flow or axial flow turbines may be used. Speeds vary from 50 to 100 rpm and usually require a double set of helical gearing or a single set of worm gears to achieve these low speeds. Therefore, they are more expensive than single reduction mixers. 

Wurm-fortsatz, m. vermiform process, -ge-triebe, n. worm gearing, worm gear, -kraut,... 

Gears should be specified as American Gear Manufacturer s Association (AGMA) requirements for cooling tower service in order to ensure an adequate minimum service factor rating of 2.0. The spiral bevel type is probably used a litde more often than the worm gear. It is also cheaper. When gears are used with induced draft applications, the... 

One of the major advantages of the worm gear is low wear, which is due mostly to a full-fluid lubricant film. In addition, friction can be further reduced using metals having low coefficients of friction. For example, the wheel is typically made of bronze and the worm of highly finished hardened steel. 

As worm gears tend to slide along their lines of contact, it is virtually impossible to maintain a hydrodynamic oil... 

An important point to remember with over-slung worm gears is that they are not immersed in the lubricant and the oil must be fed to the point of contact. The viscosity of the oil is important here, as it must not drain too quickly from the contact area. Manufacturers because of the particular lubrication problems involved with worm gears often prefer a mineral oil compounded with fatty oil. 

Table 52.6 Enclosed cylindrical and double enveloping worm-gear drives...

Worm gears of either type operating at speeds above 2400 rev/min or 610 m/min rubbing speed may require force-feed lubrication. In general, a lubricant of lower viscosity than recommended in the above the table may be used with a force-feed system. 

Warning Worm gear drives operate satisfactorily on R O gear oils, sulfur phosphorus EP oils or lead naphthenate EP oils. These oils, however, should be used only with the approval of the gear manufacturer. 

Several of the current synthetic semi-fluid lubricants for worm gears are based on a poly-alkaline glycol - which possesses slipperiness . Oxidation and rust-inhibitors are... 

Like helical gears, worms and worm gears have handedness, which is determined by the direction of the angle of the teeth. The worm and worm gear must be the same hand in order to mesh correctly. 

The worm thread is a major factor in worm ratios and is an important feature in worm design. The speed-reduction ratio is equal to the total number of worm-gear teeth divided by the number of worm threads. 

The submitters have used both an addition funnel with a worm gear delivery similar to those manufactured by Normag and an Erlenmeyer flask attached to the neck of the reaction vessel with a piece of Gooch rubber tubing. Normag addition funnels are available from Lab Glass, Inc., P. O. Box 610, Vineland, New Jersey 08360. 

Pour oil into the worm gear housing through the hole for the screw plug until the oil level is somewhat above the middle of the oil gauge glass. Screw in... 

From time to time screw out the drain screw some turns and draw an oil sample from the worm gear housing. If the oil turns out to be heavily contaminated drain it off and pour in fresh oil. The sample should be drawn as soon as the separator has stopped running. 

Slip the packing and stop ring over the shaft from the worm gear side. Lock the ring with nuts Ell. 

Fasten the protecting cover of the worm gear housing. 

Defects in ball bear. ngs and worm gear may be due to poor lubrication (bad or too little oil). ... 

Worm gear housing After each operating period of about 1500 hours See page 180-1... 

Cover - worm gear housing Packing - cover Screw - cover Washer - screw... 

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