Site map :

Various stuff
Rotation sensor
Security device
The Robot pages
Lego Ants
Robotarm v1.0
Robotarm v3.0
Tutorial 1
Tutorial 2
Physics of Lego
Measuring strength
Combining motors
Stepper motors
Lego ratchet
Electronic ratchet
1-to-2 multiplexor
2-to-7 multiplexor
RCX Mindstorms
Survey of RCX programming
The famous machines
Turing machine
New Page 1
References and links

Last upgrade to the site:
august 10th, 2002.

There has been 

access to my Lego pages since creation.

This is an unofficial LEGOŽ web site.
LEGOŽ is a trademark of the LEGOŽ Group of companies which does not sponsor, authorize or endorse this site.
You can visit the official LEGO website at:

Copyright 1996, 2000, Denis Cousineau


  1. How to measure the strength of a pneumatic?

In fact, it is not the strength of a pneumatic that we will measure, but the strength of the pump (or the tank) working behind. By attaching a weight to the pneumatic and varying it, we are looking for the point of equilibrium, the point where the weight exactly compensates the pull from the pressure tank. By measuring this critical mass, we obtain the strength of the pressure generated by the pump.

Below is a picture of the measuring device.

measure.jpg (68986 bytes)

We measured the strength of the following pumps:

Type of compressor

It can lift 

i)  The small pump 342 bricks 855 grams
ii)  The large pump with the pressure regulator 360 bricks  900 grams
iii)  The large pump without regulator 622 bricks  1555 grams
iv)   The car pump it was not available, but we suspect it can blast the above values easily.

The pressure regulator I designed limits the pressure to be less than 900 grams while it could be as large as 1500 grams. This is the point of introducing a security device: avoid overflow. At about 2000 grams, the hoses start popping out of the sockets.

  1. What is the reaction time of a pneumatic?

Pneumatics don’t react instantly. The main factors are the pressures in the hoses (generated from the pump, and maintained in the tank), and the length of them.

We tested with a hose of 3 m. If the switch is close to the tank, reaction time is slower than when the switch is close to the application. This is because the hose itself must be under pressure. When the switch is next to the application, the hose is already under pressure and ready to push the pneumatic.

Position of the switch Time to expand fully the pneumatic

Close to the pneumatic 0.25 seconds
Far from the pneumatic 0.50 seconds

As seen the difference is not large, around a quarter of a second. However, this difference increase if the number of pneumatics turned on at the same time is large.