My 2 Cyl. Shay has one R/C servo that controls the Johnson Bar. It works well, but sometimes it’s difficult to find nuetral. I’d also like to be able to get finer speed control to do switching moves so I’m considering adding a second servo for throttle.
If you use the throttle channel for throttle, what channel do you put the Johnson Bar on? On my radio all the other channels are center return. I’m sure it’s pretty easy to modify the other stick - is that what you do?
Jon Radder said:
If you use the throttle channel for throttle, what channel do you put the Johnson Bar on? On my radio all the other channels are center return. I’m sure it’s pretty easy to modify the other stick - is that what you do?
Jon, in a nutshell, - Yes. Most TXs are set up for removing the centering spring. There’s actually a Spektrum kit of a wavy strip that fits on the stick back to make the stick stay where you put it - after you remove the spring. And perhaps you want the Johnson bar to be sprung to neutral - I ran my loco like that for years before I decided to take the spring out.
P.S. I took the spring out of the throttle too.
Pictures on this old thread: http://www.mylargescale.com/Community/Forums/tabid/56/aff/11/aft/122645/afv/topic/Default.aspx
On mine Ithe left updown stick controls the throttle and the right side up/down stick controls the Johnson bar. I took the spring out of mine as well. I still have to add that strip to make the throttle stick otherwise gravity takes over lol.
I tend to use the johnson for my speed controls (you get a finer adjustment) and just leave the throttle set all the way up. I find I need to adjust te gas more then anything. I should have done a servo on the gas instead of the throttle.
You must have bought a Mode 1 transmitter. Usually (Mode 2) the letft stick is the one that does not auto-center. I wonder if anyone has been successfull with gas on a servo. It’s such a fine adjustment on mine I think it would be very hard to do on RC. You run trottle wide open (OK, about 1/3 turn on a full servo through)? That seems like a lot. I barely crack my manual throttle and the Johnson Bar ends up going full travel to get up the hill. Maybe I need to try running with it open more.
[EDIT to fix spelling but I prpbably still missed some. Fred?]
Jon Radder said:
You must have bought a Mode 1 transmitter. Usually (Mode 2) the letft stick is the one that does not auto-center. I wonder if anyone has been successfull with gas on a servo. It’s such a fine adjustment on mine I think it would be very hard to do on RC. You run trottle wide open (OK, about 1/3 turn on a full servo through)? That seems like a lot. I barely crack my manual throttle and the Johnson Bar ends up going full travel to get up the hill. Maybe I need to try running with it open more.
[EDIT to fix spelling but I prpbably still missed some. Fred?]
I might have switch the spring etc… to the otherside. Originaly I only had the throttle hooked up.
John I open the throttle as far as my servo will allow and then use the Johnson bar for speed. Makes a hudge difference (at least it does for the Forney). I can set it at one speed and walk away and it just chugs along nic,e even on grades.
The gas is very sensitive and would be tough to hook up to a servo. It would be soemthing to get use to.
Your spelling is ok as long as everyone focuses on my spelling haha
Shawn said:
Your spelling is ok as long as everyone focuses on my spelling haha
You have an excuse. You’re (is that OK Fred) married to a School teacher and you do it just for spite :o
Jon Radder said:
You must have bought a Mode 1 transmitter. Usually (Mode 2) the letft stick is the one that does not auto-center. I wonder if anyone has been successfull with gas on a servo. It’s such a fine adjustment on mine I think it would be very hard to do on RC. You run trottle wide open (OK, about 1/3 turn on a full servo through)? That seems like a lot. I barely crack my manual throttle and the Johnson Bar ends up going full travel to get up the hill. Maybe I need to try running with it open more.
Jon,
I’ve never seen anyone bother to put the gas valve on a servo, but there’s no reason you shouldn’t. Those Spektrums have 5 or 6 ch after all…
I fine tune the speed with the throttle - 1/3 to 1/2 is easy to achieve and is all you need on an Accucraft. (Though I did find a 180 deg servo for $3.50 from those HK guys - it is sitting on my bench. Seems to give more than 90 deg, though not 180.) With the 1/8" chain drive, I use a 16 tooth on the throttle and a 20 tooth on the servo, so I am getting 25% more throttle movement.
Accucraft says not to try using the Johnson Bar in other than full on/off mode, though I know you can do some control with it. I leave it full on and adjust the throttle on hills.
The gas valve needs constant adjusting as the tank heats up (next to boiler mounting) and the pressure increases, or as the pressure drops from the gas cooling down from use.
DJB engineering offers a pressure regulating valve to correct these problems;
http://www.djbengineering.co.uk/gas-reg.html
They are especially useful for ceramic burner boilers.