Sariel.pl

Very small and simple model making use of the closed pneumatic circuit idea.

Datasheet:

Completion date: 30/01/2008
Power: pneumatic (single closed circuit)
Dimensions: length 35 studs / width 9 studs / height 12 studs
Weight: 0.15 kg
Suspension: none
Pneumatics: one closed circuit

This is a good example that being fascinated by huge, complex machines doesn’t mean ignoring the simple ones. I have been interested by the idea of a closed pneumatic circuit for some time, and that was an opportunity to demonstrate how it works. A closed circuit is, as the name implies, a pneumatic circuit that works using the same, limited amount of air, that is not exchanged with the air from outside. This is unusual for Lego pneumatics, which normally requires continuous feeding by pumps or compressors, and expels air outside via the manual valves. This is also only theoretical to some extent, because in the conditions of Lego parts, as the air is compressed inside the circuit, slight amounts of it escape through the ends of the pneumatic hoses. In case of this construction, the circuit had to be refilled from outside once every 15-20 working cycles.

The construction of this pallet jack is very similiar to the real ones, while the functioning of the pneumatics is not. Just like in a real machine, there are pneumatically elevated stringers used to lift the pallets from the floor. The pneumatics needs the jack’s handlebar to be pushed downwards, which presses the air from one large pneumatic cylinder to two small ones, resulting in the elevation of the stringers. Then the entire process can be reversed – pushing the handlebar upwards causes the air to be sucked back from the small cylinders to the large one, and thus the stringers are lowered. In the real machine, however, it doesn’t work quite that way. A real pallet jack requires possibility to move the handlebar up and down at any moment, just for the manoeuvrability reasons. Thus, there is an internal pump at the bottom of the handlebar, which works when the handlebar is moved up and down repeatedly. That involves the use of a pneumatic valve, which sets the stringers to be either elevated or lowered by the pump.

Therefore, the functionality of my construction is greatly simplified when compared to the real one. It’s been, however, warmly welcomed by both Polish and international community (see the Media reference section below).

Photos:

Video:

Media reference:

TechnicBRICKs