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Doc's Casino Amusement Park Ride

Hi folks, Doc here, with one of the models that I originally designed and built to display at the 2002 ACGHS Convention in New Haven, CT. Unfortunately, circumstances prevented us from attending the event after all. For all of you, however, I am pleased to present it here in my Model Gallery, although it never quite reached its final "show quality" form, which was to include numerous aesthetic details like custom artwork, handrails, LED lighting, signs, etc. As it was built for display, I also planned to repaint all of the painted parts to really make it shine. Still, I did complete the engineering and major construction, and after some trial and error to refine the motion of the piece, the final design functions beautifully.

My goal with this model was to duplicate the motion of the real thing that I had often seen (but never ridden) at amusement parks and carnivals over the years. And I was successful, with one exception: as you may know, the "passenger wheel" on the real version raises up from horizontal to a fairly steep angle as it picks up speed at the beginning of the ride. In my version, this wheel is permanently at its final tilt angle. To check out the action of this model, click in the video window at the bottom of the page.

The key to the action of this model is that the passenger wheel must rotate in one direction while the carriage that supports it rotates in the opposite direction! Doesn't seem so difficult at first: two driveshafts could accomplish it, even when driven by a single motor. However, because one assembly sits on top of the other, the methods used to power them must be integrated together, and this was the trick. While there is undoubtedly more than one way that this could be accomplished, my solution is shown further down on this page.

As you can see from the photo at right and below, the model consists of three main sections: the aforementioned "passenger wheel" (the roulette wheel!), the rotating carriage on which it spins, and the motor unit/platform. Again, the photos show the model before all of the "trimmings" were added to dress it up. Also, the motor unit as shown here is not in its final form: it was to be bolted directly to the wooden base in the exact center of the surrounding platform. The platform is a perfect hexagon made from 12 MN base plates (I used the older, blue ones for some extra color).

The carriage that supports the passenger wheel is the heart of the model; it contains virtually all of the moving mechanical parts (see Mechanics section below). The upper end where the passenger wheel sits is canted at about a 40 degree angle. This angle could vary, but I found that 40-45 degrees worked quite well and looked good at the same time.

The passenger wheel is built much like the base of the famous 10½ Carousel model, with a ring of CS wheel segments substituting for the ring of MF base plates. N long double angles support the "floor," a ring of EZ curved girders. Each of the 8 seats is made from 2 MC base plates and one O pawl; the inner end of each seat bolts to the CS segment ring, while the pawl bolts to the outer end of the N double angle. I 21-hole strips form spokes that connect the outer ring to the inner hub (BN turret plate and T boiler) with CH angles. Overlapping E curved girders attached to the top of the boiler and to the back of each seat form the dome-like upper portion of the passenger wheel assembly. The whole thing is capped off with a boiler top and Erector flag.

Here's how it all works: the motor is set-up in the No. 9 configuration, and is mounted on its side in a cradle attached directly to the base board. A 3" axle connected to the main drive shaft with a P15 coupling passes through a plate mounted firmly above the motor. A sandwich of 2 BN turret plates and an OH 72-tooth gear is bolted to the upper plate; the drive axle passes through its center. This single axle provides all of the motive force for the entire model. The upper turret plate, in combination with a TC bearing plate and 6 TB bearings, supports the passenger wheel carriage.



The carriage itself is constructed from a variety of base plates (4 MY, 1 MD, 1 MC, 2 ME, 2 MF) plus a number of hole strips. Both the horizontal base of the carriage and its angled top section feature a pair of MY square base plates sandwiched between a pair of MF and ME plates respectively. On the base, a BN turret plate is bolted over the center hole of the lower MY, a BT pierced disk over the center hole of the upper MY (#2 in the photos below). This sequence is reversed on the top section of the carriage (#5 and #6).


A short axle passes through the corner holes of the lower pair of MYs. A P13B pinion gear is bolted to its lower end (#1), a P15 coupling to its upper end.

Things get a bit more complicated on the top section of the carriage. Originally, I used the identical pinion/axle/coupling arrangement with the upper pair of MYs, only reversed (pinion on top, P15 on bottom). I then connected the two P15s with a short section of OE flexible coupling. While this worked, it did not produce the exact results I had been looking for (more on this later). So, I was forced to modify the arrangement.


First, I removed the P15 from the lower end of the short axle and capped it off with a DB motor pulley. Next, I bolted two K 11-hole strip bracket to the front side of the the upper section, one facing out, on facing in. I ran another short axle through the inner set of holes on the outer bracket. A P15 went onto the lower end of this axle, a P49 18-tooth gear on the upper end (#4). Finally, I dropped a third short axle through the inner set of holes on the inner strip bracket and attached another P13B pinion gear to its upper end. As the photos show, both the P49 and the two P13s all mesh together.

As with the motor cradle, the passenger wheel has a sandwich of 2 BN turret plates and an OH 72-tooth gear bolted to the bottom of its hub. An axle fixed to the hub passes through this sandwich, extending several inches below the bottom of the hub. Another TB/TC bearing set is placed on the BN atop the carriage (#5).

The base of the carriage is dropped onto the motor drive shaft, and the screw in the BT on the base (#2) is tightened onto the shaft. The axle protruding from the bottom of the passenger wheel is slipped through the bearing plate and BN on top of the carriage (#5), and then through the BT disk on the MY below (#6). The pinion gears at top and bottom of the carriage now mesh with the OH gears on the passenger wheel and motor cradle respectively.

When the motor is turned on, the drive shaft turns the carriage in a circle. As the carriage rotates around the OH gear below, the pinion gear meshing with the OH is turned as well. The rotating pinion shaft turns the flexible coupling, which turns the P49 gear on top of the carriage. The rotating P49 turns the two pinions meshing with it, the second of which turns the OH on the bottom of the passenger wheel, thereby turning the passenger wheel itself. The end result of this compound motion is that the passenger wheel rotates while oscillating up and down as it turns, just like the real thing!

But, let's back up for a second: why was all of this business on the top section of the carriage with the extra gears necessary? As I described above, my first design used the identical, but reversed, pinion/axle/coupling arrangement on both the base and top sections of the carriage, with the two P15s connected by a piece of OE flexible coupling. This configuration produced the opposite rotation I needed for the carriage and the wheel, but it also produced an identical rotation speed for both assemblies. I knew that this would be the result, of course, but didn't suspect that it would be a problem until I watched the model run. That's when I realised that the wheel must turn faster than the carriage in order to produce the proper motion. When the wheel and carriage turn at the same speed, the wheel does not appear to rotate at all (even though it really does), but merely appears to rock up and down. This is a neat, although unexpected, optical illusion, but it wasn't what I was after.

So, to increase the speed of the passenger wheel relative to the carriage, I needed to use a larger gear (but not too much larger) on the top of the carriage. A P49 turned out to be just the thing. However, getting the P49 to mesh properly with the OH required some experimentation with positioning. The only hole spacing on any Erector part that permits an OH and P13 to mesh properly is between the center and corner holes of the MY square base plate. Because the P49 is larger than the P13, I couldn't use the corner hole for it. But, I still needed a P13 in a corner hole to mesh with the OH. So, the question became: how do I get the P49 to mesh with this P13? After much trial using different plates and brackets to try and position the P49 properly, I eventually found a way to mount it.

But this resulted in a new problem: introducing a second gear caused the wheel to rotate in the same direction as the carriage! Which meant that I now needed to add a third gear in order to reverse the rotation of the wheel once again! After still more trial and error, I arrived at the gearing combination and positioning you see in the photos above.