The continuous compressor loading will make the uncontrolled air pressure increase in mainreservoir1 and main reservoir 2 tanks, to safeguard the main reservoir tanks ,and to reduce the unnecessary power loss of compressor above the consumed system air,
there are various stages to reduce the increase in air pressure by
Electro pneumatic controlling unloaders of compressor,
safeguard the main reservoir tanks with safety valves that operates if cut in cutout fails,
reduce the unnecessary compressor load of hp,
reduce the moisture content in main reservoirs with auto drain valve,
Electro Pneumatic Governor
It is, located at expressor room. It maintains Main reservoir air pressure between 8 to 10 kg/cm2. MR1 air is connected to EPG through a cutout cock.
A pressure switch is provided in nose compartment, which gets MR1 air supply through a cutout cock.
Whenever MR pressure reaches 10 kg/cm2, the pressure switch closes and gives supply to EPG coil.
In turn EPG will send MR air to unloader assemblies provided on inlet valves of LP and HP cylinders and open them.
Since inlet valves are kept open, pistons will make idle strokes. There will not be discharge of air. So, MR air pressure will reduce.
This is called Unloading.
Whenever MR air pressure reduces to 8kgs/cm2, pressure switch will open and supply to EPG will be disconnected.
EPG will exhaust the air which was already supplied to un-loader assemblies. So inlet valves will close and normal compression will take place.
This is called Loading.
During unloading, air from EPG will go to auto drain valve also, to drain out moisture from MR1.If EPG struck up and MR air pressure dropping,
close EPG COC and slightly open MR1 and MR2 drain cocks.
Main Reservoir 1 and Main Reservoir 2
It stores the compressed air which is coming from the compressor unit. There are two reservoir each having 350 Lts.
Capacity.
A safety valve is provided to protect the MR1. It reservoir 10.5 Kg/cm2.
There is a one way check valve provided in between MR1 and MR2 which allows air in only one direction. MR1 is located at loco left side under truck.
MR2 is located at loco right side under truck. In WDM3D, this MR1 and MR2 are located at loco left side under truck. In this loco,
MR1 is located just below the compressor in the under truck.
Auto Drain Valve
This automatic drain valve is provided near
MR1. This operates at specific intervals for draining
the moisture from the reservoirs. Whenever the
compressor governor is doing unloading, auto drain
valves also open and release the MR air so that the moisture in the air will be discharged. When loading starts they will close.
Manually operated drain cocks are also provided in MR1, MR2, J filter and
control air reservoir to drain out the moisture and keep the air system clean and moisture free.
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