Air System BOM
QTY DESCRIPTION 3 1/4" BALL VALVE 6 1/4" NPT TO 1/8" NPT REDUCERS 2 COLDER 1/8" FLOW COUPLERS COLDER MFG. MC 1002 2 COLDER 1/8" FLOW WITH 1/4" BARB INSERT COLDER MFG. PMC 2204 1 1/8" NPT CHECK VALVE CLIPPARD MJCV-1 1 AIR CYLINDER DOUBLE ACTING BIMBA 092D 2 1/8" NPT PIPE TEES 1 AIR TANK (CONVERTED PROPANE TANK) SEVERAL FEET OF 1/4" COPPER LINE ASSORTED 1/4" FLARE OR COMPRESSION FITTINGS
NOTES:
Because of the variance in the construction of individual cars the
number of pipe fittings and the quantity of copper line required varies.
Use the drawing to determine the air flow and the type and quantity of fittings
required to make the connections.
The 1/4" ball valves I buy from my local hardware store. These valves are the small body type and fit well under the frame line of a standard 1/8th scale car. The valves are made in Italy and are distributed under the B&K brand name. The double acting air cylinder I bought from Air-Dreco in Dallas but I have found that several acceptable substitutes are available. For example: W.W. Grainger carries an air cylinder under the Speedair name with the same specs Its number is 6W090. Depending on where you source this item here is a cross reference:
Bimba SPEEDAIRE CLIPPARD AMERICAN PARKER HUMPHREY 092-D 6W090 SDR-17-2 1062DNS2 1.06DSR2 6-D-2
The check valve I also bought from Air-Dreco in Dallas it is a Clippard model MJCV-1 it is a in line 1/8" npt female to 1/8" npt female with a cracking pressure of 1.5 psi I have not found a more convenient source for these but any decent brass 1/8th flow check valve should work.
The coupler in between cars are made by Colder Mfg. These are a 1/8" flow quick
connector made in a chrome plated brass. The chrome plated brass parts are
mounted on the cars. The interconnect between cars is made out of a length of 1/4" tubing
that have the mating insert made by Colder installed on both ends of the interconnect.
The inserts are attached using a single wire tie to act as a hose clamp.
This insert is made out of Delrin part # PMC 2204 so under emergency situations the
delrin insert will break away applying the brakes on all the cars. The Colder
rep. that I buy from is Wilson Company in Ft. Worth.
Revised information:
You can get the Colder couplers from MSC at
www.mscdirect.com
The car body connectors (MC 1002) are MSC number 62197298.
and the inserts for the car interconnects (PMC 2204) are MSC number 48608863.
The last major item in the air system is the air tank. I use an old propane
tank. The kind that you use on your propane torch. These are very easy to
come by and I just hate throwing them away!
I convert these by removing the schrader valve in the neck and then filling
the tank with a light oil. This chases any residual propane that is left in
the tank. ( I have visions on one blowing up if I don't do this ) Cut the
gas fitting off at the base of the neck with a band saw or hacksaw. Finally
drill out the hole in the top of the tank and tap the hole in the tank for
a 1/8" NPT. Now drain the oil from the tank this will chase out all the chips
that you made when you drilled and tapped the tank. This coating of oil in
the tank will also help keep the air devices lubricated in the car and keep
corrosion down on the inside of the tank.
Mechanical System BOM
QTY DESCRIPTION 1 SET Mountian Car Co. brake hangers 1 CLEVIS for cylinder 1 STOP NUT for cylinder 1 NOSE BRACKET for cylinder 1 EQUALIZER BAR 2 1/4 28 x 2" bolts drilled per mechanical drawing 2 1/4 28 stop nuts 1 CABLE ADUJUST BRACKET 2 BICYCLE BRAKE CABLES SETS 2 1/4 20 x 1" Bolts 4 1/4 20 x 1/2" Bolts 2 Aluminum screen door rollers 2 Pulley brackets
NOTES:
The mechanical system has gone through some evolution since I started
this project. Revision A of the drawings show the brake hangers on the truck
activated by a reach rod into a cable strung across the arms of the hangers.
this was adjusted by a turnbuckle in the reach rod. This worked but it had
problems. The first problem encountered with this system is the reach rod
sat to low to the track and tended to pick up weeds and grass in the right
of way. This was a minor annoyance since if the right of way is free of
grass this is not a problem. Second problem was the brakes did not apply
with an acceptable force at 40 psi and the cable across the arms of the
brake hangers constantly streched requiring adjustment all the time. The
problem ended up when I entered tight curves the reach rod would not slide
on the cross cable reliably and the brake would partially apply. With all
these problems I made Version B. Version B works well even though it has
some more components and is more complicated to build.
The basic design of the mechanics results in pulling motion to apply the brakes This force is relayed by the cables to the trucks where the small pulley mounted on one of the arms translates the cable pull to a right angle with the truck where the cable compresses the arms together to apply brakes.
The most complicated piece on the system is the pulley that translates the motion 90 degrees. This is made out of a 3/4" diam. aluminum with internal ball bearing screen door roller. The keeper bracket is made out of a T shaped piece of sheet aluminum that is folded to mount on the hole in the roller and retain the cable in the groove of the roller. The cable adjust bracket is made out of a piece of angle drilled and tapped for the two special 1/4 28 bolts that are center drilled the stop nuts lock these down in the bracket. All the cable stops were made from the 1/4 20 x 3/4 bolts which were drilled to accept the cable so it could be locked against the arm by compression.
Again the mechanics can be made any way you want so long as the system is made to accept a pulling motion to apply the shoes to the wheels.