There are many of these old-timers chugging around the world and still doing the job. Some of you perhaps never saw one of these and never will, but you should know about it in the event you need one for a specific application. These compressors come in a variety of sizes from one (1) hp up. They can be used for air conditioning or refrigeration application. The biggest advantage of this type compressor is the choice of driving power you want. The compressor has a drive shaft protruding from it. The shaft can take either a pulley or a coupler. For instance, I’ve serviced a unit such as this that was driven by a six-cylinder internal combustion engine fueled by propane. The greatest advantage of this application is the capacity control. With the engine throttle linked to the thermostat, the engine idles when there isn’t a load demand. This type compressor can be driven by electric motor, internal combustion engine, or turbine. Another great advantage to this compressor is that it can be installed in an area that doesn’t have ample electrical power to drive large compressors.
For all the good, there has to be a little bad. The two biggest drawbacks about the open-drive compressor is its physical size and the critical alignment. As you can see in Fig. 3-10 there has to be a close alignment between the compressor and the driving force. If the alignment goes out, beyond specifications, the front shaft oil seal will begin to leak. Both refrigerant and oil will exit here. Alignment with a dial gauge at regular intervals is prudent.