Video Presentation

Specifications

• Steam bicycle powered by a single pneumatic engine (unmodified)
• Switchless Pneumatic Engine using pinching hose loop
• Single camshaft with 4 pushers for the 4 pinching hose (air in/out for each chamber)
• 5:1 gear ratio for the inertia wheel
• 2-Speed gearbox using rotating gear shifter with a side lever on the reservoir
• Working throotle on the handlebar (intake pinching hose loop) with idle setting
• Working rear “speed reducer” brake using friction rope on pulley
• Steering on the front wheel with the handlebar
• Side stand (display model only)

You can read the full review of this model on my blog.

Performances and building note

The performance are quite good considering the purpose of the engine : to be built with non modified parts at a standard running air pressure (3 bars). It runs fine and can achieve good speed (nothing compare to a modified LPE with thousand RPM) and accept to run low too. But, it has also drawbacks linked to the heart of how it works.

The first is the hoses used for the 4 loops which make the distribution (4x 9cm lenght) : they have to be soft enough to have an easy pinching and strong enough to handle the pressure. For instance, the last hoses in the 42100 are glossy and hard to pinch, the very old pneumatic hoses from 90’s is too soft for me and do not handle the pressure. The ideal hoses are those which come from the sets from some year like the 8436, or the 8455 (mine comes from this set), you can use also the hose from the 8110, 42043 if they are not the glossy version. You can use other hoses but you will need to increase the pressure if the hose is too hard to pinch and reduce if it is too soft (with of course limits). As I have not tested, I can not certify it will work with every hose. Blokbricks alternative hose has been tested on a smaller engine and works fine. They can be purchased in meter.

The second drawback is that the air flow and air pressure affect the required pinching force and then affect the functioning.  The air flow have to be constant to avoid the problem of running, that is why I do not recommend to use it with Lego pump and/or airtank (like this one) but rather an other source of air like a compressor / pump with a air reservoir which enables to have a constant air flow (not in the instructions nor the bil of material). The LEGO Hand Pump works but the functioning is jerky. The air pressure is less sensitive but I notice it runs the best with the hose I have between 2.5 to 3.5 bars. Less than this value, the engine has not enough power to run and stop, and with more pressure, the hose do not handle the pressure. 

I have not seen any wear on the hose, even if they tend to keep the shape of the loop some time after dismantling, they recover their original shape without any leak or damage after some time. But I think it can be damage if they rest for a long time on display with no pressure. So if you display this creation, remove the upper pneumatic T connector assembly to loosen the loop.

How to build ?

You only need the parts and the instructions. You can purchase the PDF instructions on this shop and build it with your own LEGO parts. The instructions contain the partlist at the end, but you can check individually on Rebrickable.

About this product

Instructions preview

How to set up

Lego Pneumatic Engine is hard to make it work without previous experience. That is why I have made a video to explain step by step how to set up, how to choose the hose, and which part and placement are important. Please watch this video before buying the instructions and please consider that your engine can not run at first time and require fine set up. It is better if you have already an experience in building and setting Lego Pneumatic Engine. You can contact me using the contact form if you have trouble to make it works.

Please note that you need to have you own source or air (3 bar / 40psi, with constant flow). You can use :

• 4x pump lego like this one (not recommended)
• Use a LEGO compressor according to the specs
• Use a electrical compressor like automotive compressor, industrial or electrical pump, you will need to put the air in the LEGO hose with . You can use a ball needle.
• Use a hand pump with ball needle.

Please carefully follow this video :