G-Scale Funicular Modeling Tips
Updated 1/17/20
Here are a few things that are important to know when designing a functional model funicular that’s driven by a motor. See separate list of Parts Suppliers. Consult design drawings to see where the parts go.
Power Source Selection: Use a 12V DC constant power source made for outdoor use. Waterproof power sources are available. 12V is more than adequate for the slow moving cable system, controller, sound module, and lights. It stresses the light bulbs less than a 24V source. I used a waterproof 35 watt power source protected in an outdoor electrical box purchased separately.
Motor Selection: Use a small high torque 12V DC motor with integral gears. 60 rpm works great. If motor has integral gears you will be able to use fewer reduction gears for a simpler system. Only use motors that can be securely attached to a motor mount of the correct size. Protect motor in a water-proof Gear Room.
Gear Selection & Calculation: To reduce friction, jamming, excess noise, over-complication, gear box size and headaches, use the fewest number of gears that will give you your desired gear ratio. With my system, only two gears are needed! Beveled gears are the best for loads and even wearing. They are better than sprocket gears and much better than worm gears. Use only metal gears, not cheap plastic. Solid Brass Meccano Gears are the BEST! Keep gears greased and oiled. My bevel gear arrangement has a 3:1 gear ratio (36 teeth/12 teeth). So if the motor is 60 rpm, the main drive pulley will rotate at 60/3 = 20rpm. If the Drive pulley has a 9” circumference, then in theory it will move the cable 9” x 20rpm =180”/minute = 3”/sec at full power. Actual measured speed was slightly higher, but the throttle knob fixes that. At nine volts, the cable moves at 3"/sec. A throttle will give you the exact speed you want.
Pulley Selection and Uses: There are two main types of uses for funicular pulleys:
1) The big Drive Pulley (also called “drive wheel”) moves the cable. You want to maximize friction between the cable and Drive Pulley so that the cable won’t slip which causes jerky movement or no movement at all. It should have a “V” groove and be as large as possible (3” diameter is good). The cable should be in contact with the pulley along as much of its circumference as possible to maximize friction. To do this use two directional pulleys close together and close to the drive pulley. I call these two “pincher pulleys”. Use the Meccano 19b pulley for the Drive Pully. Don’t use plastic pulley.
2) Directional Pulleys change the direction of the cable. You want to minimize the friction of the cable against directional pulleys. To do this, avoid large angle changes to the cable when you design your system. Also minimize the number of pulleys in your design. Pulleys with ball bearings have less friction on the pulley axle. Don’t try to minimize cable friction by using light weight cars! Model funiculars work much better with heavy cars of equal weight because they add friction between the cable and the Drive Pulley. Don’t use plastic pulleys. I used 7/8” steel pulleys with ball bearings. Real funiculars will also use smaller directional pulleys or rollers between the rails along the entire length of the track to hold up the heavy cable which would sag and rub the ties without them. They also use tilted small pulleys to direct the cable around the curves in the passing switch. I found that these directional pulleys along the track were unneeded in my G-scale model since the cable tension provided by my heavy cars prevents the tiny cable from sagging onto the rails. This really simplifies cable management!
Cable Guard Importance and Location: At the top of the track there is a small “U” shaped cable guard made from a bent 1/16” thick brass rod with two pieces of brass tube around the two pins of the guard. It is located close to and below the top set of directional pulleys. After the cables leave the pulleys they pass between the two pins of the guard. Its purpose is to maintain the two cables in exact alignment with the nearby two directional pulleys as the cars move along the upper straight section of track. Since the directional pulleys are in the center of the track and the cable hooks on the cars are off-center, the hooks would move the cable towards the outside rails as the cars ascend. Without the cable guard, the cables would not align with the pulleys and might cause the cables to jump off the pulleys.
Cable Selection and Modification: Carpenters’ string was great for some of the initial testing, but don’t use it on your final model or any string or rope that will stretch over time. DO NOT USE: fishing line, cotton, hemp or nylon string! Stretching will cause the cars to stop and pass incorrectly! Avoid the use of ball chain too.Only use flexible stranded stainless steel cable of the thinnest diameter possible. Thin cable is more flexible than thick cable and will bend around the pulleys better. Also, it is more prototypical. The 1/32” marine cable I used is perfect. To determine cable length, place both cars exactly opposite each other in the exact middle of the ABT passing switch. Keep cars in place using clamps placed on rails. Cut a piece of cable slightly longer than you’ll need (about 8 ft.). Make an eye loop on one end of the cable using the included cable crimps, then thread the rest of the cable through all the pulleys, cable guard, and rail gaps. Connect the eye loop to the hook of one car, then loop the other end through the cable hook of the other car. Pull the cable so it becomes taught, then make another eye. A hemostat works great for holding a cable loop together until you crimp it. Cut off excess cable then test.
Cable Hooks for Cars: Use 1/16” strong thin steel rod to make cable hooks for cars. Don’t use thicker rod because it might hang up in the ABT switch cable gap. Don’t use brass rods which might bend under load. Cut rod with Demel cut-off disk. Bend with needle nose pliers and hammer. Insert and glue stem of hook into an attachment bracket (I used a small triangular piece of ¼” acrylic sheet) at the bottom of the front of each car, slightly off-center on the same side as the double flanged wheels. The hook should be as small as possible and be slightly below the top of the rails so it passes through the gaps in the switch. If set too low, the hook will hit the rail spikes. If set too high, the cable won’t pass through the rail gap. The correct hook height requires great precision and must be determined by testing!. Test the hook before you glue it to the attachment bracket!
Magnet for Car: Only one car has a small neodymium magnet underneath which activates both the Circuitron AR-2 controller and the sound module by tripping two reed switches located between the rails at each station. Use the smallest magnet possible and locate it 1/8” above the top of the rails. A small magnet is more precise because it will let you stop the cars at exactly the right spot. The large magnetic field of a large magnet is less precise. Do not put magnets on both cars! The MM-D-10 style magnet I used is flat mounting with a female threaded shaft permanently attached. Screw a short piece of threaded rod into the hole under the flat car that was meant to attach a coupler. Screw the small threaded flat magnet in the other end of the rod. The screw allows you to easily adjust the height of the magnet. This is the perfect magnet for a funicular!
Car Wheel Selection and Modification: Use the biggest and heaviest steel wheelsets you can find. Remember, heavy cars are a good thing! Don’t use plastic. This helps keep a low center of gravity in the cars. Modifying the wheels is easy and fast. Grind off the flange on one wheel of each set by putting the axle in an electric drill and grinding it off against a disk sander. Epoxy a 1½” steel fender washer to the other wheel of each set to create a double flanged wheel.
Car Design Types: Funiculars, like most vehicles, need nearly horizontal floors and seats for passengers’ comfort and safety. So on steep inclines, funicular car frames have a different angle than the passenger compartments. Usually, small short cars have a single horizontal floor with seating. But long cars often have two or more floors. I call these split-level cars. Split-levels require ramps or stairs for boarding in the stations. Although harder to build, they do have a lower center of gravity which is safer, and they are more interesting I think. (See the adorable Budapest Funicular).
Car Lighting: Don’t electrify the rails! You’ll have a big electrical short between the inner rails in the ABT passing switch. If you want car lighting, you must use onboard 9V batteries. Since these batteries have steel casings, you can save space by attaching to a thin magnetic disc glued underneath the flat bed. You can use electrified rails in a four rail funicular however. Obviously, there would also be a short in a three rail funicular.
Adding and Removing Cars: Before connecting the cables to the cars, make sure that the ends of the cable are next to each other near the middle of the track. After connecting one car, be sure to hold it firmly until you connect the other car. Don’t accidentally let go of it or it will fall down the track and crash! Likewise, before you remove a car, make sure you stop the cars next to each other in the center of the passing switch. (I put two compression contact springs from D-cell flashlights on the wood bumper at the bottom to protect the car in case there is a runaway someday!)
I’ll add to this list as I think of other things.
