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point motors

Posted: Wed Mar 05, 2014 8:16 am
by scalemaster
I need to fall back on point motors to control ground signals , the problem is layout is run on a lever frame connected through slide switches.

I know that that point motors need to have passing switches and suitable discharge units to opperate.

Due to the fact I can`t change the slide switches does any of our members know of an electricle circuit that would act like a passing swich powerd from the 12v fed dpdt slide switch?

All of the points and semephore signals are controlled by wire and Tortoise motors.

I have lots of hammant & morgan point motors that I can use.

Can anyone help I need a diagram.



Re: point motors

Posted: Wed Mar 05, 2014 8:55 am
by Tim V
I would suggest that H&M motors are not suitable to drive ground signals. They are very light things, and easily destroyed by the motors. Suggest you use something else, less violent.

Re: point motors

Posted: Wed Mar 05, 2014 10:28 am
by LesGros
scalemaster wrote:
...I know that that point motors need to have passing switches and suitable discharge units to operate...

As Tim points out, solenoid motors are vigorous in their action. From your description, I take it that there is insufficient space to use the soft-action Tortoise under board and adjacent to the signals. Conrad motors have a soft action and a lower profile.
It could be possible to use wire-in tube to connect the ground signal remotely to a point motor mounted at the edge of the board.
DCC Supplies have the Modratec WIT kits which use plastic covered curtain wire as a Bowden cable. It is similar to the cables used on bicycles. Another option is to visit your local Flying Model shop; this leads to the possibility of using R/C servos. But to use these you would also need to add a control board.
It might be helpful to look up Keith Norgrove's description of his use of servos.

best wishes

Re: point motors

Posted: Wed Mar 05, 2014 9:21 pm
by grovenor-2685
If the H&M point motors are in good condition you do not need either passing action switches or a capacitor discharge unit. They work very well off a normal 16V ac accessory supply using an SPDT switch, slide or toggle, and using the built in switch on the motor to cut off power as it throws. This circuit used to be in the instructions for the H&M.
It does rely on the built in switch working correctly so you need to check that. Good for points but I also would not recommend for ground signals unless you make sure the mechanical linkage cannot overstress the signal parts, even then the action will be to fast.

Re: point motors

Posted: Thu Mar 06, 2014 5:12 pm
by martin goodall
While on the subject of point motors (the double-solenoid type, e.g. Peco, Gaugemaster, etc.), I am proposing to use this means of 'nudging' the Vincent de Bode / Ray Hammond ('Davin') swinging arc pendulum operated signal movement mechanisms. The actual drive to the signal will be the gravity-driven swing of the pendulum arm, but I propose that the change to the centre of gravity of the fulcrum that starts the swing in either direction should be electrically driven (e.g. by double-solenoid point motors as mentioned above). There are practical reasons for doing it this way, rather than by a simple mechanical push or pull, despite a purely hand-driven mechanical device being the more obvious method to use.

On the other hand, I want to avoid the loud 'thwack' or 'thud' that is often associated with these solenoids. Can anyone say which is the quietest double-solenoid point motor available, and to what extent noise attentuation might be obtained by flexible mounting under the baseboard? Some lost motion as a result of a flexible mounting would not be a problem in this application. Would solenoids intended for N gauge be quieter? I have some ancient Post Office relays, but they would probably need a highish voltage (24v, maybe 50v ?) to power them.

Any thoughts?