Just for play play I dcided to make an LPE. This si what I came up with.

Its and inline 4, made as simple as possible. There are only 2 valves, regulated by crankshaft on one side and another crankshaft on the other side.

Its a very simple and slow engine, but it works!

Here's an LDD file of it,I used round 1x1 bricks as color ccong for tubes.

DOWNLOAD LDD

Also a short vid:

Looks great,whick makes me wounder if i used my 5 small rams would i be able to make a smaller one?

Are you going to build a small car to fit it in you could use switch one ram for a pump to power the steering.

Wow so simple and yet so effective, nice job.

tim

You should try the 120° three cylinder engine with special connecting rod like scotch yoke or other. You can also modify the setting of the crankashaft with the 4 cylinders : 4*90° or 2*180°, the important point is the switching mechanism linked to the cranshaft.

Here is a explanation why (a sort of begining) :

http://www.nico71.fr/lpe3i/

The major problem when designing a Lego Pneumatic Engine (LPE) is the dead points of the switches. In deed, the switches are the most important parts with the cylinders, they enable the engine to distribute correctly the energy (air-pressurized) in the cylinders. The problem is when a switch is on its dead point, no energy enter or no get away from. The result is consequently a blocking during the rotation of the engine.

There are different ways to reduce the dead point (evaluate at 30° of a complete revolution of the crankshaft). The first method is to use a inertia wheel also called flywheel in order to give enough inertia to the engine to break the dead point(s). The problem will be then the vibration at high speed (amplify by the mass and inertia). The second method is to modify the mechanics : for instance with the scotch yoke instead of the classic connecting rod which reduces the dead points.

The third factor to consider is the number of cylinder. For instance, a 1-cylinder engine can’t start itself without flywheel. Two or more cylinders is necessary to have a automatic start but you must set up the crankshaft at 90°. If you set up the crankshaft at 180° (in classic real explosion engines), the engine will not start by itself, again because the Lego parts have not enough inertia. If you want more than 2 cylinders, be aware that a lot of cylinders will generates lot of friction. That is why, a configuration angled at 60° with 3 cylinders is a good compromise to start with.

In any cases, you engine is a good start !

Edited December 30, 201113 yr by nico71

Nice start!

Some time ago I've used another way to reduce the dead point using a rod with more radius on the crank and a slider on the switch valve

Hi Zblij :)

This engine will be in Your Tatra?

Proboably not, but maybe when i make it faster and better it may be in a supercar!