Pack 7 - Stage 35. The gearbox.

[Mark, The Master Modeller]

Stage 35 gives us the gearbox which allows the electric motor to drive the two steam engines and the propellors.

When the ship is going forward all three props are driven, but when the ship is going astern only the two outer props are driven.  The centre prop is driven by the steam turbine and you can't reverse a steam turbine.  The gearbox incorporates a gear in a slot to realise this feature.

Take the 4 shafts and insert them into the holes in the gearbox.

You may wish to apply a little lubricant to the shafts now, then fit the 4 type A cog wheels.

Add the three type 3 cog wheels.  I added a little lubricant to the holes in the gearbox casing before fitting these.  You only need a thin smear.

Add the type D cog in the centre.  Again, I added a little lubricant first.

The instructions now tell us to add lubricant to the shafts and teeth of the cog wheels.  We've already done the shafts, so we just need to apply some to the teeth of the cogs.  I didn't have enough for all the teeth so I used some other grease that I had in the hobby room.  Virtually any grease will do.  Anything from Vaseline to grease for RC cars, to general purpose grease sold for use on cars.  

Then add the two type B cogs.  On goes in the slot on the left which allows the steam turbine shaft to only rotate in the forward direction and to stop when the engines are reversed.  The other cog allows the port shaft to rotate in the opposite direction to the starboard shaft.  I love this attention to detail.

Fit the gearbox cover and secure with 7 screws.  Tighten these up evenly so the gearbox covers doesn't twist.

This completes the assembly, but let's test the gearbox.  Insert a shaft into the hole for the motor.  Turn it clockwise and all three prop shaft sockets rotate.  Turn it anti-clockwise and only the outer two sockets rotate.

 

This completes the stage.