Railway Point Control Circuit & Point Indication Circuit
Railway Point Control Circuit & Point Indication Circuit:– Fig 3.2 shows the point control circuit for an ‘N’ style frame. The differences here are the RC and NC lever bands which are used for the energization of the respective Reverse and Normal point auxiliary valves. Note that these lever bands are similar ones for the WL energization. Therefore when the lever is placed either Normal or Reverse the point control circuit and the WL circuits are energized at the same time.
To prevent a race between the two circuits the WL is fed from the electro-pneumatic valve via a 1/4″ (6.35 mm) bore air hose. This small bore ensures that the WL will retract from its port much quicker and before the point motor has started to move the point escapement and therefore catch on the WL.
The Point Indication Circuit
Fig 3.3 shows the point indication circuit found on ‘N’ style frames. It looks identical to the ‘V’ style circuit. The difference here is that the indication lamps are fed from 100V AC and are located immediately behind the relevant point lever on the frame, labeled N and R.
‘N’ Style Four Foot Point Circuits.
‘N’ style circuits are similar in principle to those associated with ‘V’ style frames.