Mamod William II actually completes a continuous run
Posted: Sun Mar 17, 2013 8:41 pm
Despite the various modifications added to the William II it still had a history of not running very well, with a common theme of having to stop after slowing down to raise more steam pressure before resuming a run.
As has been seen with the Thomas Telford prototype testing these locomotives on an endless supply of compressed air proves little with it's steaming capability.
Having spent a fair bit on Steam4Fun beautifications for my William II it has been a long running workshop battle to get it to run properly.
One thing I noticed from the various videos of Mark I, Mark II & Brunel locomotives is that the piston gland added to their cylinders has not always stopped steam/condensate leaking past. Measuring my William II piston glands I found that the 'O' ring on the piston rod does not get compressed at all. Not being able to remove the piston rod big end without damaging the rod I cut another 'O' ring with a sharp knife and placed it on top of the current 'O' ring. I had then done up the piston gland with a spanner, but recent experience has found that they only need to be done up finger tight to be effective but not affect performance.
I drilled out the burner venturi to 6mm and it's performance has improved well. I fitted a copper gas pipe but had decided to have the gas tank mounted so the valve was accessible from the back of the cab. With the tank being mounted at the front of the cab control of the valve is hidden by the cab roof, so I will modify this copper pipe so the tank is mounted with the valve accessible from the side of the cab (also means the hole cut in the cab roof lines up with the filler valve again).
There is too much play sideways with the wheel axle bearings but I have not found a satisfactory method of holding them in place so far without de-riveting the chassis frames. So I have cleaned up and straightened the coupling rods and added some washers so they do not catch on the wheels.
Yesterday I managed to achieve a continuous run with this William II, albeit with only one loaded coal wagon. Having found my Steam4Fun modified Mamod safety valve (the current Mamod safety valves release at 40 PSI but they release sideways which disturbs the hot air/burnt gases at the top of the side tanks and thus affecting the burner - Steam4Fun used to sell a nice turned safety valve cover which is a very tight fit over the Mamod safety valve so that it now releases vertically) I have just achieved another continuous run this time with 2 loaded wagons by carefully adjusting the gas valve & regulator throughout this run.
I do now wonder if changing the piston 'O' ring to a red viton 'O' ring would help, but I'm unaware of how the remove the piston gland housing without some major metal work - I have seen a William cylinder dismantled where the owner tapped a thread into the far end of the cylinder block and then screwed in a threaded drift to force the piston and piston gland housing out.
Chris Cairns.
As has been seen with the Thomas Telford prototype testing these locomotives on an endless supply of compressed air proves little with it's steaming capability.
Having spent a fair bit on Steam4Fun beautifications for my William II it has been a long running workshop battle to get it to run properly.
One thing I noticed from the various videos of Mark I, Mark II & Brunel locomotives is that the piston gland added to their cylinders has not always stopped steam/condensate leaking past. Measuring my William II piston glands I found that the 'O' ring on the piston rod does not get compressed at all. Not being able to remove the piston rod big end without damaging the rod I cut another 'O' ring with a sharp knife and placed it on top of the current 'O' ring. I had then done up the piston gland with a spanner, but recent experience has found that they only need to be done up finger tight to be effective but not affect performance.
I drilled out the burner venturi to 6mm and it's performance has improved well. I fitted a copper gas pipe but had decided to have the gas tank mounted so the valve was accessible from the back of the cab. With the tank being mounted at the front of the cab control of the valve is hidden by the cab roof, so I will modify this copper pipe so the tank is mounted with the valve accessible from the side of the cab (also means the hole cut in the cab roof lines up with the filler valve again).
There is too much play sideways with the wheel axle bearings but I have not found a satisfactory method of holding them in place so far without de-riveting the chassis frames. So I have cleaned up and straightened the coupling rods and added some washers so they do not catch on the wheels.
Yesterday I managed to achieve a continuous run with this William II, albeit with only one loaded coal wagon. Having found my Steam4Fun modified Mamod safety valve (the current Mamod safety valves release at 40 PSI but they release sideways which disturbs the hot air/burnt gases at the top of the side tanks and thus affecting the burner - Steam4Fun used to sell a nice turned safety valve cover which is a very tight fit over the Mamod safety valve so that it now releases vertically) I have just achieved another continuous run this time with 2 loaded wagons by carefully adjusting the gas valve & regulator throughout this run.
I do now wonder if changing the piston 'O' ring to a red viton 'O' ring would help, but I'm unaware of how the remove the piston gland housing without some major metal work - I have seen a William cylinder dismantled where the owner tapped a thread into the far end of the cylinder block and then screwed in a threaded drift to force the piston and piston gland housing out.
Chris Cairns.