Load dependent control arrangements

DETAILED DESCRIPTION Having thus described our invention what we claim is: 1.
A load sensing arrangement comprising: load sensor means for generating an analogue electric signal dependent on a load; electric signal conversion means coupled to said load sensor means for converting said analogue signal to a binary signal having a mark-to-space ratio dependent on the magnitude of said analogue signal; electrically operated fluid valve means coupled to said conversion means to alternately open and close a fluid valve in accordance with the marks and spaces in said binary signal; a source of predetermined fluid pressure coupled to said fluid valve means to have said predetermined fluid pressure alternately passed and blocked by the opening and closing of said valve to produce an output of said fluid valve means which is dependent both on said predetermined pressure and on said load.
2.
The arrangement of claim 1, wherein the load sensor means comprises a strain-to-electrical transducer capable of modifying an electrical signal in dependence on the load.
3.
The arrangement of claim 2 wherein the dependency of said transducer on the load is proportional dependence.
4.
The arrangement of claim 1 wherein said fluid is a gas.
5.
The arrangement of claim 4 wherein said gas is air.
6.
The arrangement of claim 1 including a fluid capacity coupled to the output of said fluid valve means to dampen fluctuations in the pressure of said output.
7.
The arrangement of claim 1 including a fluid pressure amplifier means coupled to the output of the fluid valve means to amplify the fluid power of said output of said fluid valve means.
8.
The arrangement of claim 7 wherein said fluid pressure amplifier means is a self-lapping relay valve.
9.
The arrangement of claim 8 wherein said relay valve has a control volume coupled to receive the output of said fluid valve means, said control volume being dimensioned to present a fluid capacity for damping pressure fluctuations in the output of said fluid valve means.
10