As Norman says most small engines do not have rings or have labyrinth seals but with double acting steam engines the piston is very thin when compared to an IC engine and some form of ring or seal is necessary.
I am building Gauge 1 (1/32nd scale) British pattern locomotives with 1/2" bore steam cylinders.
I have used traditional graphited yarn and modern O'rings but am not completely happy with either.
The former is fiddly to apply and the latter suffers from stick-slip , ie. when stationary the O'rings grip the cylider walls rather tightly , often requiring a push to overcome this.
I have been experimenting with cast iron rings and have had some success even though the rings are so delicate that breakage is common.
I am sure Norman and the older members will have come across Cords piston rings .
These were/are? made of spring steel and were very thin, three rings would fit into a piston groove , the gaps being staggered at 120 deg to each other.
This configuration allowed a good seal to be restored to a bore that had worn oval.
So has anyone tried to make rings of this type ? I will try the idea out when I can find the time.
Dan.
I am building Gauge 1 (1/32nd scale) British pattern locomotives with 1/2" bore steam cylinders.
I have used traditional graphited yarn and modern O'rings but am not completely happy with either.
The former is fiddly to apply and the latter suffers from stick-slip , ie. when stationary the O'rings grip the cylider walls rather tightly , often requiring a push to overcome this.
I have been experimenting with cast iron rings and have had some success even though the rings are so delicate that breakage is common.
I am sure Norman and the older members will have come across Cords piston rings .
These were/are? made of spring steel and were very thin, three rings would fit into a piston groove , the gaps being staggered at 120 deg to each other.
This configuration allowed a good seal to be restored to a bore that had worn oval.
So has anyone tried to make rings of this type ? I will try the idea out when I can find the time.
Dan.