What are all those extra lines for on the front of a SD40-2??

Question

I was wondering what those hoses on both sides of the front cow area of a SD40-2 are used for? Three on the engineers side, and two on the breakmens side.

Answer 1

There are 3 hoses on each side of the unit on both the front and back besides the main air brake pipe.They are called MU hoses for multiple engine hook up.One is main reservoir and is pressurized to whatever the main reservoirs have in them(usually 130 to 150 psi).Next is the actuating hose which is empty til the engineer bails the brakes when he makes a set of the train brakes.Then it's pressurized to keep the engine brakes from applying.Next is the application and release hose for the engine brakes.Pressure on it depends on how many pounds of independent brake the engineer has applied.Older units also had a 4th hose for wheel sand.And of course they have an MU cable for electrical connections.

Answer 2

All diesel locomotives that are set up for Multiple Unit (MU) operation are so equipped.  They allow pneumatic transfer of control impulses from the master unit to the slave units.

Answer 3

Main Reservoir:  Connects all the engines' main air reservoirs, nominally 140 psi.

BC Equalizing:  Stands for "Brake Cylinder Equalizing" or "Application and Realease" as above.  The engine brakes.  These onnect all units in the consist.

Actuating Pipe: Puts main reservoir air into certain ports and passages when the engineer "bails off" the engine brakes.  The engine brakes will apply from an "automatic brake application" (train brakes).  But, to keep control of slack it is often desired to keep the engine brakes released, so the engineer "bails off" the engine brake by depressing a handle, putting air into the actuating pipe, keeping the engine brakes released.  

Since the engine brake can be operated "independently" from the train brakes it is often referred to as the "independent brake."  It is also called "straight air" or "jam."  "Jam" is a holdover from the earliest days when the first locomotives were equipped with the "steam jam brake," which simply put steam into a cylinder that pressed brake shoes against the engines drivers.

The pipe in the center is the brake pipe, which carries air to the rest of the train.  

Between each unit is also the "MU cable," or "jumper," which links all the units' electrical systems.

Hook 'em up, test your air and you're ready to go...

Answer 4

multiple unit controls lines, and air brake lines.

You see similar on both the front and the back.