Atlas Copco C146 Unloader Kit Replacement – 2906095700

Atlas Copco 2906095700 – C146 Unloader Kit

The Atlas Copco 2906095700 (2906-0957-00) C146 Unloader Kit is a service kit used in the unloading/control system of oil-injected rotary screw compressors. The unloader mechanism controls compressor inlet loading by regulating the pneumatic control of the inlet valve, allowing the compressor to switch between loaded and unloaded operating conditions.

Working Process:
During compressor start-up, the unloader mechanism helps keep the compressor in an unloaded or low-load condition while the motor reaches operating speed. This reduces the starting load on the drive system and allows the compressor to start smoothly.

Once the compressor reaches normal operating speed and the control system commands the compressor to load, control pressure changes the position of the unloader mechanism. The inlet system opens and allows atmospheric air to enter the screw compressor element. The air is then compressed and delivered into the compressor’s air/oil separation circuit.

During loaded operation, the unloader mechanism remains in the required operating position so that the compressor can produce compressed air according to system demand. The control system continuously monitors pressure and adjusts the compressor’s loading condition as required.

When the discharge pressure reaches the unloading set point, the controller sends an unload command. The unloader mechanism changes position and causes the inlet system to close or restrict the incoming air. At the same time, the compressor’s internal pressure is controlled so that the machine can continue running with a substantially reduced compression load.

This load/unload process prevents the compressor from producing unnecessary compressed air when there is insufficient downstream demand. It therefore helps reduce energy consumption and mechanical loading during unloaded operation.

The 2906095700 C146 Unloader Kit restores the mechanical and sealing components of the unloader assembly when they become worn, damaged, contaminated, or unable to maintain the required pneumatic control. Atlas Copco’s official component list includes a valve, guide, guidance tape, spring, bushing, seals, O-rings, washer, and other assembly components. The official listed kit weight is 798 g.

During maintenance, the compressor must be stopped, isolated, and completely depressurized before the unloader assembly is serviced. The existing components are removed, and the valve body, passages, and mating surfaces are inspected and cleaned. The replacement components supplied in the kit are then installed in the correct positions and orientation.

After assembly, the unloader should be tested through the complete compressor operating sequence. The compressor should start in the correct unloaded condition, load smoothly when required, unload at the specified pressure, and return to loaded operation when system pressure falls.

A worn or malfunctioning unloader can cause failure to load or unload, continuous air intake, excessive power consumption, unstable pressure, air leakage, hard starting, or abnormal compressor operation.

Correct installation and maintenance of the 2906095700 C146 Unloader Kit helps restore reliable load/unload control, reduce starting and unloaded operating stress, maintain stable pressure, and support efficient compressor performance.

Part Number: 2906095700
Alternative Number: 2906-0957-00 / 2906 0957 00
Part Description: C146 Unloader Kit
Brand: Atlas Copco
Component Type: Compressor unloading/control-valve service kit
Application: Oil-injected screw compressors
Known Application: C146 / GA90–GA160 applications
Official Listed Weight: 798 g
Primary Function: Controls compressor loading and unloading through the inlet-control system
Main Benefits: Smooth start-up, reliable load/unload operation, reduced unloaded power consumption, stable pressure control, and improved compressor reliability.

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