Roundhouse "Jack" hunting

[The mechanic]

Can someone shed some light on a problem that is bothering me?

I have recently acquired a Roundhouse "Jack". The loco is late 1980's vintage but very good condition nontheless. The issue that I have is that at low to medium regulator opening, in forward or reverse gear, the loco regularly "hunts" or surges.
I have to note that the slightest touch of the regulator handle or valve block, results in a change of speed/ surge.

I have a few locos now and know what to expect, but have not encountered this sort of issue before. The loco has been dry-stored for around 10 years by its previous owner and considering this, the problem is very minor but it is annoying! Are these Roundhouse regulator valves known for promoting "hunting"? I would be interested to know if others have suffered this problem and what the cure is, I.e. Can you strip them and pack them with suitable grease/lubricant to prevent surging?

Regards

Dave

 

[Gavin Sowry]

The term 'Hunting', as used in real railways, relates to the wheels pushing against one of the running rails, on straight track (a common problem with the older style 3 piece bogies of American type).
Is this what you are getting?, or is the loco 'surging'.... indicating that, perhaps the valves need resetting. Do you have a bent axle, or wobbly wheel?

 

[Moonraker]

My understanding is that there are two types of regulator; one for manual control and one for radio control. They differ in the length of the needle point. Is it possible that the wrong type of regulator is fitted to the loco.

Easiest solution is to email Roundhouse about the problem and attach a video if possible.

Regards
Peter Lucas
MyLocoSound

 

[dunnyrail]

My initial thoughts were that the wheels or perhaps just one set were out of Gauge somewaht. But further description appears to defy that. Your discussions with Roundhouse may suggest a new Regulator, pretty sure that would sort the problem.

 

[PhilP]

Might it get better with some 'running-in'? - Or has the loco been used a reasonable amount, in it's past-life?

 

[maxi-model]

Dry storage 10 years - Check the condition, and if not perished, try a wipe of grease around the "O" rings on the regulator and gas regulator shafts. If that fails check the the valve timing and order yourself an RH "service" kit, piston seals, etc', for that loco. And call RH anyway Max

 

[The mechanic]

Thanks for the replies. I forgot to add that the loco was running on blocks as I have no line to run on at present. The steam circuit, boiler, pipework, lubricator and cylinders where all surprisingly steam-tight externally.

By "hunting" I was using the automotive meaning of the term when applied to internal combustion engines, i.e. rhythmically speeding up and slowing back to original speed, and not the American railroad terminology as related to above.

When I next steam the loco, I will get a video clip to illustrate the problem.

Dave

 

[Paul M]

Silly thought, is the reverser in the correct position? On one of my locos, if I knock the reversing lever it gives the same action as you are describing.

 

[The mechanic]

Ah! You may be on to something there. The servo horn on the reverser servo had split when I received the loco.
I replaced the horn and set it centrally on the servo so that there is equal throw either way. Maybe a bit of tweaking is required? The only issue I have with this theory is that the same "hunting" happens in both forward and reverse gear and the rhythm is also identical. It really is "doing my head" this one!

When I get chance, I will fire the loco again and take some film footage, we can then " compare notes".

Dave

 

[artfull dodger]

I have found that live steamers that are stored for years, need a few boiler fills run thru them before things loosen back up and seals reseal themselves. Worst case, do a cylinder rebuild with the kit from Roundhouse. Most likely there is gooey steam oil in the various passages and pipes, more run time on blocks or if you can visit someone's railway and pull a moderate load for a few boiler fills. Then reevaluate Jack's performance.

 

[Romney]

It sounds like your Jack is priming. This is where if the boiler is dirty, water is carried over through the regulator instead of dry steam. Once in the superheater, the water flashes to steam, this will make your loco speed up, then settle again. If it has been stored for ten years it is highly likely your boiler needs a washout. This me as simple as changing the water a few times. Remove the safety walve and look into the boiler. If the previous owner has used tap water it may be very chalky and require a desaler to remove.

 

[dunnyrail]

It sounds like your Jack is priming. This is where if the boiler is dirty, water is carried over through the regulator instead of dry steam. Once in the superheater, the water flashes to steam, this will make your loco speed up, then settle again. If it has been stored for ten years it is highly likely your boiler needs a washout. This me as simple as changing the water a few times. Remove the safety walve and look into the boiler. If the previous owner has used tap water it may be very chalky and require a desaler to remove.

Some suggest a dose of vinegar added to the cleaning process, do not like it myself but I guess after a good flush out with clean water ought to cause few problems.