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There are few equipment markets more competitive than rough-terrain radial and arm and drill forklifts (RTFL). In 1999, rough terrain forklifts reached their sales zenith at 15,525 units. Current market conditions are another story, and today, press sales are radial roughly half of what they were in 1999. This condition is predicted to increase by only 3 percent in the coining year.This no growth situation has left manufacturers in the position of having to grow by taking market share away from arm their drill competitors and the most effective way to do that in ninny cases is to supply the low cost machine. Yet even with the emphasis on reduced cost, performance and control are still key requirements in the marketplace. So how can a manufacturer keep costs down but offer a machine that performs above the current low-cost machines? Most air-cooled products (including chillers, rooftop units, and condensing units) use DX evaporators. Most DX systems allow oil to travel through the refrigeration circuit and back to the compressor oil sump. Great care must be taken during design to provide oil return, particularly at part load, when refrigerant flow rates are reduced.Water-cooled press chillers often use flooded evaporators. In a flooded evaporator, even small amounts of oil can coat evaporator tubes and significantly diminish chiller performance. radial This can lead to an elaborate oil-recovery arm and drill system. Magnetic bearings eliminate the need for these systems press and oil management in general. In fact, radial the only required regular maintenance of the compressor is the quarterly tightening of the terminal screws, the annual blowing off of dust and cleaning of the boards, and the changing of the capacitors every five years. Complete service agreements and extended maintenance contracts can be provided by the manufacturer. THE MOTORMost hermetic compressors arm use induction motors cooled by either liquid or suction-gas refrigerant. Induction motors have copper windings that, when alternating current is run through them, create the magnetic fields that cause the drill motor to turn. These copper windings are bulky, adding size and weight to the compressor.Two-pole, 60-Hz induction motors operate at approximately 3,600 rpm. A higher number of revolutions per minute can be obtained by increasing the frequency. press Compressors that require radial higher shaft speeds tend to use gears. While gears are a proven arm technology, they create noise and vibration, consume power, and require lubrication.The magnet-bearing compressor features a synchronous permanent-magnet brushless DC motor with a completely integrated variable-frequency drive (VFD). The stator windings found on conventional induction motors drill are replaced with a permanent-magnet rotor. Alternating current from the inverter energizes the armature windings. The stator (excitation) and rotor (armature) change places. No commutator brushes are required. The motor and key electronic components press are internally refrigerant-cooled, so no special cooling is required for the VFD or the motor.
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