Refurbishing a Mamod locomotive cylinder.
Posted: Sat Feb 21, 2015 9:47 am
Hi,
I am still working on putting together a Mamod locomotive using some bits and pieces that I have. The cylinders which are old and well used have already had '0' rings fitted to them but their rods moved a lot sideways in the cylinder cove. This is caused by two points of wear the hole in the cylinder cover and the hole in the piston where it is resiliently mounted on its rod . These two points of wear cause the piston rod to rock in the cylinder and can cause the piston to jam or run roughly in the cylinder. This problem an be cured by fixing the piston to its rod and bushing the cylinder cover. The photographs show, I hope, how this can be done.
This cylinder mounted on the chassis.
The front cylinder cover is removed by supporting the cylinder putting a rod through the hole in the big end and hitting the big end with a hammer.
A soft punch is used against the piston to remove the rear cylinder cover.
Removed piston assembly, the '0' is in good condition and wasn't replaced.
The rivet over a washer and a '0' ring holding the piston to its rod.
Removing the big end using a rod which is twisted back and fore to release it.
The piston parts. Notice the recess in the cylinder cover there is only about a 2 mm bearing length in it!
A new piston rod with a shorter larger shoulder turned on it.
Piston riveted to a new rod.
An extended bush fitted to the cylinder cover increasing the bearing length from 2 mm to 8 mm.
Body back on chassis for an air test.
Regards Tony.
I am still working on putting together a Mamod locomotive using some bits and pieces that I have. The cylinders which are old and well used have already had '0' rings fitted to them but their rods moved a lot sideways in the cylinder cove. This is caused by two points of wear the hole in the cylinder cover and the hole in the piston where it is resiliently mounted on its rod . These two points of wear cause the piston rod to rock in the cylinder and can cause the piston to jam or run roughly in the cylinder. This problem an be cured by fixing the piston to its rod and bushing the cylinder cover. The photographs show, I hope, how this can be done.
This cylinder mounted on the chassis.
The front cylinder cover is removed by supporting the cylinder putting a rod through the hole in the big end and hitting the big end with a hammer.
A soft punch is used against the piston to remove the rear cylinder cover.
Removed piston assembly, the '0' is in good condition and wasn't replaced.
The rivet over a washer and a '0' ring holding the piston to its rod.
Removing the big end using a rod which is twisted back and fore to release it.
The piston parts. Notice the recess in the cylinder cover there is only about a 2 mm bearing length in it!
A new piston rod with a shorter larger shoulder turned on it.
Piston riveted to a new rod.
An extended bush fitted to the cylinder cover increasing the bearing length from 2 mm to 8 mm.
Body back on chassis for an air test.
Regards Tony.
