Then air is admittedto the gauge under low pressure Vas used 'inlballoon tires it willbe appreciated that the air pressure alone would not be A'sutlicient to yelongate therubber sleeve 23 and spring 25 and move the sleeve 2O a sufiicient distance to registerthe correct air pressure admitted to the gauge on the scale. The provision of the spring 26 which acts in the capacity ot a booster spring prevents any possibility o an inaccurate reading being given as it assists the air pressure in moving the sleeve 2 to the correct reading position.
It will bc sccn in this case that as the sleeve 2 moves along the passage. It has been found that in using gauges of the standard type in conjunction with air line nozzles that they are apt to become distorted and inaccurate when the nozzle is used for intiating truck tires which carry a high air pressure as such air pressure would enter the'gauge subjecting it'- to a strain and actuating it beyond the limit of its movement.
For eliminating this occurrence and preventing undue strains upon my gauge I provide the valve 29 which is operated in the following manner and cuts oil' the entry of air into the gauge when a suiiieient, predetermined pressure has been reached. The rubber seal presses against the lip of the valve stem to prevent air from leaking during the measurement, and the pin depresses the valve pin in the valve stem to let air flow into the gauge.
The air will flow around the pin, through the hollow passage inside the sphere and into the piston chamber. When the pressure gauge is applied to the valve stem of a tire, the pressurized air from the tire rushes in and pushes the piston toward the right. The distance the piston travels is relative to the pressure in the tire. The pressurized air is pushing the piston to the right, and the spring is pushing back.
The gauge is designed to have some maximum pressure, and for the sake of example let's say it is 60 psi. The spring has been calibrated so that psi air will move the piston to the far-right of the tube, while 30 psi moves the piston half-way along the tube, and so on. When you release the gauge from the valve stem, the flow of pressurized air stops and the spring immediately pushes the piston back to the left.
The spring is not shown in this figure, but the calibrated rod fits inside the spring. The calibrated rod rides on top of the piston, but the rod and the piston are not connected and there is a fairly tight fit between the rod and the stop.
When the piston moves to the right, it pushes the calibrated rod. When the pressure is released, the piston moves back to the left but the rod stays in its maximum position to allow you to read the pressure.
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Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. The piston head 37 isprovided with a leather cap packing 37 The piston head 37 has a stem or rod 38 extending therefrom which extends upwardly through the partition Mounted within the space above the partition 39 is the block 40 in which the resistant element 41 is mounted, against which the laterally bent end 42 of the rod 38 is adapted to wipe.
One of the wires of the system connects to the barrel 28 as at 43 while its second wire extends from the u per end of the resistant element 41 to the binding post 44, the interior of the compartment above the partition 39 being lined by a di-electric material As is clearly shown in Fig.
The opposite side of the battery has a lead 46 which extends to one side of the cylindrical measuring instrument 47 which is an electric meter calibrated in pounds to indicate the pressure of the air in the tires. The opposite side of the gauge 47 has a line 48 extending to the switches 49, 50, 51 and Our website uses cookies. By continuing to use it, you agree to their use. Further information Agree. Contact Us. Leave a Reply Click here to cancel reply Name.
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