OVERVIEW OF READING MB PNEUMATIC DIAGRAMS AND PORT IDENTIFICATION
Understanding Pneumatic Diagrams Port Numbering Mercedes-Benz use a standard method for that allows for easy identification of the pneumatic system. The various ports on any valve are divided into categories: Supply Tank Port Port Air Pressure In -Inlet Usually supply from an air tank or another component. Air Pressure Out - Outlet Line in which air travels to a component. Solenoid Eg: Exhaust Brake Port 3 Port Exhaust / Vent (to atmosphere). Where air is exhausted directly to atmosphere. Control Line. Usually a line in from that controls/regulates the operation of a component. Component Eg: Exhaust Brake In some cases where there are more than one inlet or outlet an additional number appears AFTER the first number. This is to indicate the sequence of the port in the valve. Eg: Port Eg: Port 3 Indicating the first outlet Third Outlet Indicating an outlet Outlet This is more common on larger components Eg: way distribution valves.
Common Components Below is a list of common components found in Mercedes-Benz Pneumatic diagrams and a brief explanation. Compressor Generates the air for the air system. Port is an optional control line that unloads the compressor when the system is full. Zyklon 3 Air Dryer / Cyclone Filter. As its name suggests it removes moisture from the system as air passes through a filter with decadent. The Cyclone filter removes any oil from the system by centrifugal force. 0L Air Tank. Supply reservoir for the air system. The 0L indicates a 0litre capacity.
Restrictor Primary function is to slow the rate of air passing from one pint to another. Eg: to act as a time delay for exhausting air. One Way Valve. To allow air to flow in only one direction. In the example shown air can only pass from right to left. x.5 Air Line. Nothing unusual here except it is important to note that the x.5 indicates a mm diameter line with a.5mm thick wall.
Air Ram Cylinder. Converts air to mechanical force. When energised with air mechanically pushes out a ram to mechanically actuate a component. Eg: Exhaust Brake. Not actuated Spring Pressure keeps ram retracted. Actuated Air pressure overcomes spring Pressure, pushing ram out. Air in
Shuttle Valve Has two inlet ports and one outlet port. Allows two separate air supplies to control a component. Usually one of the supplies is a main supply and the other is a is a back-up (safety) and is Identified by the smaller line. In the event of the main air supply failing, the inlet port closes and the other side has greater air pressure and takes over. Normal operation Main supply has priority flow on valve. Back up Smaller line continues to supply air pressure. No air Main air in Back-up air pressure Back-up air
Solenoid Valve. Designed to either block air flowing to a component or to allow air to flow to a component. Electrically actuated or Pneumatically actuated. ELECTRICALLY ACTUATED Not Energised - air is blocked. Air Energised Air may flow through. Air Electric Solenoid Electric Solenoid PNEUMATICALLY ACTUATED No Air on Control Line Air is blocked Air Air on Control Line Air may flow through. Air Control Line (no pressure) Control Line (pressure)
3/ Way valve Designed to allow air to flow to a component or to allow air to exhaust from a component. Electrically actuated or pneumatically actuated. ELECTRICALLY ACTUATED Not Energised - air is exhausted to atmosphere. Air in Energised Air may flow through. Air in Electric Solenoid Electric Solenoid Air out PNEUMATICALLY ACTUATED No Air on Control Line - air is exhausted to atmosphere. Air on Control Line Air may flow through. Control Line (no pressure) Control Line (pressure) Air out
Control Valve. To control (vary) the amount of air flowing to a component against spring pressure. Mechanically or pneumatically controlled. PNEUMATICALLY ACTUATED Low Pressure on Control line Low pressure High Pressure on Control Line High pressure from Port from port. MECHANICALLY ACTUATED Plunger slightly depressed Low pressure Plunger further depressed High pressure from Port from port. Mechanical Plunger Mechanical Plunger