Posted August 20, 201212 yr Most of you out there hate how 9v track always drops voltage at the far end of the track. Also, I'm sure that most of you hate the ludicrous cost associated with fully motorizing a PF-powered train. The cost of these methods, the hard-to-find 9v track and the expensive PFs, is too high. In concert with the recent rising in the amount of steam locomotive MOCs, why not install a computer-controlled air compressor in the tender of the locomotive, then run the hose through to the cylinders? In other words, why not make pneumatic locomotives? Right now, pneumatic components aren't particularly expensive, and economic prudence would tell locomotive builders to at least try this method of construction. Not to mention that there is insane pulling power that can be yielded from these cylinders. Using the equation -----c P (d)^2 s TE = ----------- ----------D Please note that these figures are calculated for the 64mm pneumatic cylinders and BBB large driver wheels. This also assumes that your compressor is operating at at least 20 psi. c = 0.85, P = 20psi, d = 2(0.5), s = ~2.52, D = ~1.2, we find that -----0.85 20 2(0.5)e2 2.52 TE = --------------------- = ~35.7 lbs. --------------1.2 That's an insane amount of power for a LEGO locomotive; however, if you use different drivers and air pressures, your figures might be different. Even if it is slightly financially unwieldy to have a pneumatic train, just look at the benefits! Your locomotives would be able to pull far longer trains than any 9v or PF locomotive!
August 20, 201212 yr Even if it is slightly financially unwieldy to have a pneumatic train, just look at the benefits! Your locomotives would be able to pull far longer trains than any 9v or PF locomotive! Honestly, LEGO Trains as a hobby is in itself "slightly financially unwieldy" but anyways.... I only quoted the last part of you post because I think you're over simplifying the issue of increasing train length. The biggest 2 problems I've encountered are the magnetic grip strength of the couplers and the amount of traction (or lack thereof) where the rubber meets the rails! Neither of these issues would be addressed by going Pneumatic.
August 20, 201212 yr Author Honestly, LEGO Trains as a hobby is in itself "slightly financially unwieldy" but anyways.... I only quoted the last part of you post because I think you're over simplifying the issue of increasing train length. The biggest 2 problems I've encountered are the magnetic grip strength of the couplers and the amount of traction (or lack thereof) where the rubber meets the rails! Neither of these issues would be addressed by going Pneumatic. kyphur, What you said is true. However, if one were to replace the existing magnets in the couplers with neodymiums that have some ridiculously huge strength, then overall the length of the trains would increase dramatically because you can afford to stack more cars on and not worry about the magnetic fields that bind the cars together. Frankly, I think that your statement on the amount of traction that the locomotive has is irrelevant. That is because this thread only covers the method of locomotion, not the locomotives themselves. The issue of traction on the locomotive would have to be dealt with by the builder of the locomotive, just like any other power system, whether it be 9v or PF.
August 20, 201212 yr I'd have thought a bigger problem (literally) would be that the Lego pneumatic parts are quite sizable and would need a fair amount of room to operate I'd have thought. It'd certainly be cool to see someone try though.
August 20, 201212 yr Pneumatic Lego trains have been done: That's a model by Rene Kok. I also found this thread here on Eurobricks. I see a few problems with this approach. First size. You think a battery box + receiver + motor is tricky to hide in a model? Now add a compressor! Efficiency. I wonder if you really will get more power by converting electric power into pneumatic pressure first. Rene's engines are indeed powerful, but they run on a proper compressor. Still, I'd be interested to see some experiments...
August 20, 201212 yr Author Pneumatic Lego trains have been done: - image snip - That's a model by Rene Kok. I also found this thread here on Eurobricks. I see a few problems with this approach. First size. You think a battery box + receiver + motor is tricky to hide in a model? Now add a compressor! Efficiency. I wonder if you really will get more power by converting electric power into pneumatic pressure first. Rene's engines are indeed powerful, but they run on a proper compressor. Still, I'd be interested to see some experiments... That space crisis can be alleviated if one were to replace the receiver and battery box with an RCX, NXT, or Scout hotwired to an IEEE 802.11n-compatible transceiver and then have the motors and compressor hidden in the tender. One must remember that the only thing the motor powers is the compressor, and not necessarily the cylinders. Regarding efficiency, the total amount of air compressed would depend on the gearing of the compressor, not so much the size or output torque of the motor.
August 20, 201212 yr Author An RCX to save space??? I was only using the as examples of microcontrollers. Plus, an RCX can fit into a tender if it is rear-facing and turned 90°, or placed into the well of a condensing tender.
August 21, 201212 yr The costs of a PF train aren't that high at all, giving that they built a perfectly working LiPo etc. Of course 60€ might seem expensive, but a LiPo always is and LEGO did a great job. It runs for quite a while with considerable trains and is difficult to destroy even when shorting it etc.
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.