Gears installation

Assembly of front reducer assembly l.Install the adjusting washer in the drive bevel gear, install the big bearing inner race of drive bevel gear by press. 

Gear Box Input/output speeds, type of gears installed and lubrication system provided. 

Backlash is an important factor in proper spur gear installation. A certain amount of backlash must be built into the gear drive allowing for tolerances in concentricity and tooth form. Insufficient backlash will cause early failure... 

Consider a 1,200 kW power reeovery expander-gear-generator designed to be installed in parallel with a natural gas pressure letdown station. The expander shown in Figure 1-2 reeeives the proeess gas at 11 bar and 42°C and expands it to 5 bar. In this ease, the temperature at the diseharge is ealeulated to be 1°C, and sinee the gas eontained water vapor, it will eondense in the expander. This will bring the gas to a suitable dew point, and droplets are removed in a separator downstream of the expander. 

The first documented use of dry gas seals in turboexpanders was in 1989. At that time, an ethylene plant in Scotland worked with a dry gas seal manufacturer to retrofit a turboexpander-integral gear-generator package. The partial success of that project was sufficiently encouraging for both user plant and turboexpander manufacturer to undertake a redesign of all three expander stages. Dry face or gas seals were installed at that time. 

Gears, wherever used, can be a major source of problem and downtime. This standard specifies the minimum requirements for special-purpose, enclosed, precision, single- and double-helical one- and two-stage speed increasers and reducers of parallel-shaft design for refinery services. Primarily intended for gears that are in continuous service without installed spare equipment. These standards apply for gears used in the power industry. 

For 3,600-rpm compressor drives below 5,000 hp, simplicity of installation almost dictates using the two-pole induction motor. No gear e. required, and the overall electrical and mechanical installation is the simplest possible. 

For the slower speed compressors, an evaluation must be made concerning the use of direct-connected motors that are more expensive, or the use of a less expensive 1,800 rpm or a 1,200 rpm motor with a speed-reducing gear. As before, the evaluation must include all factors, such as installation and the extra space, as well as some factor for additional maintenance. 

The low speed gear shaft and the housing must be designed to permit installation of a stub shaft for a torsiograph unit if an operational problem occurs. API 613 gives the details of the shaft end requirements for attaching a torsiograph. This should be done on all synchronous motor compressors and on multiple driver or multiple compressor case trains. 

Most mixers are driven by electric motons, or in some cases by mechanical turbines, with gears ratioed to give the proper performance speed of the impeller. A variable or 2-speed driver or gear system often proves worth the extra cost, since it is difficult to predict the exact speed requirements for some new installations. This is particu-... 

Figure 10-175 illustrates the assembly of a typical forced draft unit with electric motor and gear drive. Note that walkways and access ladders are necessary to reach the exchanger connections where valves are usually installed. If... 

The oil pump is usually gear driven from the crankshaft so that it will start pumping oil immediately on start-up of the compressor. In compressors that work in an oil-free system, oil injectors are not used. Oil separators are installed on the discharge side after leaving the aftercooler. 

Gear couplings When properly installed and maintained, gear-type couplings do not generate a unique forcing function or vibration profile. However, excessive wear, variations in speed or torque, or over-lubrication results in a forcing function. 

Oil is fed to meshing zones by wide jets or sprayers, and uniform distribution across the tooth faces is necessary to avoid local distortion. Clearly, the rate of flow is important the effects of too little oil are easily imagined. A sound practice is to position an extra jet on the exit or disengagement side of a meshing zone, where the teeth are at their highest temperature. If gears run in either direction, sprayers must be installed on both sides. 

Under better conditions, mechanical lubrication may be used. Force-feed lubricators can be installed that will provide a continuous and measured supply of oil to the meshing teeth or by spraying atomized lubricant onto the gears. 

The three most likely types of operational service misuse are overloading, incorrect lubrication and the presence of contaminants. Overloading is primarily due to the use of too small or too weak a gear unit, and this may be the result of false economy (installing an available unit for an application beyond its capacity) or failure to cater for the effects of shock loads in calculations of power rating. 

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