Disneyland Monorail - differences from Walt Disney World

Update March 2017 - an auxiliary circuit board allows the high current to the motor to bypass the original Disney circuit, allowing us to use higher powered motors. This is now a standard upgrade for Disneyland WhisperJets.


Update July 2016 - I finally tested the motor drive circuit of a Mark VII model to see how much power it can deliver to a motor. The answer is "not much". At 230 mA, about what the stock motor draws, the voltage drop is about 0.2 V. At 500 mA, what a faster motor may draw, voltage drop is up to 0.5 V. It gets worse as the current draw goes up, to the point where the power is limited and the voltage drops to where the monorail will probably stop.

The solution, if we want more speed, is to power the motor with a different circuit (like a DRV8838) and control that circuit with the original outputs to the motor.


Back to the original article:

The DL Mark VII monorail has a number of differences from the WDW Mark VI (and DL Mark V), the most obvious is the remote control. This is not radio control but infrared. The controller has buttons for Forward, Reverse, Stop, and Sound. The simulated beacon on the roof of the monorail is the infrared receiver, cover it and the monorail will not accept commands from the controller.

Inside are more changes: of course the small circuit board is different since it has circuits for controlling the motor and sound; the wires all plug into connectors making the monorail easier to assemble (and disassemble); the front lights are now on the lower shell, the only thing on the upper shell is the battery tray and it plugs into a connector on the circuit board. The power switch does not actually switch the power, it controls a solid state switch on the circuit board. Because of this the batteries are never disconnected but the current draw when it is off is too small to measure (with my equipment).

The switch is probably rated for less than 500 mA and would not last long switching the battery power. A new switch will have to be installed to convert the monorail to RC or we could add an elecronic switch controlled by the existing switch (this is the preferred method as it keeps the original switch).

The sound is also controlled by the circuit board and can not be triggered with a switch (or a radio receiver output). Two solutions: use a different sound chip, copy the sound to a PC, then copy it to the new chip. Easy. ;) Method 2: program a microcontroller to mimic the signal sent by the Disney remote and send that signal to the original sound chip (embedded on the circuit board). Method 1 can give custom audio clips and better sound while method 2 keeps the original parts.

The drive train is very different, the gearing is new with a crown gear instead of the worm gear. To get a suitable final ratio there are three gear reductions: 10:24 from the motor; 10:32 second; and 10:40 final for a total of about 31:1. Another addition, the shaft with the drive wheel has a clutch, probably to protect the gears from someone pulling the monorail along the beam while it is not running.

The monorail set a new speed record around my test circle and not in a good way! It took 29 seconds to complete the circle and the motor drew about 0.26 amps. Obviously this model is slow but easy on batteries. Opening the motor showed why, the armature is wound with 0.15 mm wire, the smallest I have found on one of these 3 V motors. This is good for motor and battery life but we may grow old before the monorail gets to the next station!

Stock motor
260 mA (runtime > 4 hours), 0.15 mm wire
2.80 V (drop from 2.87 open circuit)
29 seconds around 44.5" loop (~140" circle)

The new motor is not labeled as a Mabuchi like in some older monorails but a "S M C Motor" product. My oldest model has a Mabuchi, the newer ones have the SMC clone which is almost indistinugishable from the Mabuchi. This may be a division or joint venture of Mabuchi.

I never felt the monorail was too slow but this one changed my mind! So what to do? On the WDW monorail it is easy to install a faster motor but on the DL monorail there is a potential problem. I corresponded with someone who tried a faster motor and he reported that the monorail would stop after a short time, then run again after a short time ...repeat. The motor is controlled by circuits on the board, my first guess is that the circuit is getting hot from the extra current and shutting down until it cools off.

I designed a relay circuit that moves the motor current from the circult board to the relay. It works (and only costs about $4) but does not allow reverse. A second relay would allow reverse but I did not follow through on that because the fellow was happy with running in forward only.

Two solutions:

1 - install a motor driver board like Pololu's DRV8838 board to control the motor. The motor driver board would get it's signals from the original PC board for FWD / REV / STOP.

2 - install a Deltang receiver and get full speed control in forward and reverse along with radio control of lights and sound (and rear lights and horn if you want one). Along with the radio I would also install a faster motor like Tamiya's "Torque Tuned", the Deltang Rx60 is good for more than enough power.

The gearbox could be modified for less reduction and that would also increase the speed,again with an increase in motor current. One thing is for sure, this one needs more speed! :) The gearbox is also noisy due to the inexpensive gears and so many of them.


Update: a Tamiya "Torque Tuned" motor controlled by a Deltang Rx60 receiver easily powered the monorail around the test circle in about 12 seconds, pulling 600 mA. That is much more than double the original speed!