US 2371909 A
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Description (OCR text may contain errors)
March 20, 1945. D. NAERB FLUID OPERATED SWITCH Filed Nov. 19, 1941 Patented Mar. 20, 1945 FLUID OPERATED SWITCH Daniel Naerb, Stavanger, Norway; vested in the Alien Property Custodian Application November 19, 1941, Serial No. 419,'194 In Norway December 1, 1939 3 Claims.
cylinder which is in communication with the aforesaid cylinder, the raising of which latter piston causes a signalling device located at the street-crosslng to come into action.
Apparatuses of this kind are known, in which the piston set in motion by the pressure of the liquid directly moves a mechanical signal, and
I further are known apparatuses in which the said piston acts upon an electric switch for lighting up an electric signal-lamp. The present invention involves an apparatus of the last-mentioned kind, in which the signalling apparatus comprises one circuit for a clear"-signal and one circuit for a "stop"-signal, and its purpose is first of all to provide for such an apparatus an electric switch which will be more reliable in its iunctioning than those employed in the hitherto known apparatuses of this kind. 4
The characteristic feature of the apparatus according to the invention consists mainly in the fact that the making and breaking of the circuits for "clear, and "stop-signals are effected by means of a contact-member, mechanically connected with the piston moved by the pressure of the liquid, which member during the movement of the said pisten from its 'lowest to its highest position brings about an electric connection firstly between two stationary switchelements in the cle'ar'-signa1 circuit and afterwards between two such elements in the stop"- signal circuit.
The further objects and advantages of the invention will appear from the following description with reference to the annexed drawing, which diagrammatically illustrates an arrangement according to the invention.
In the drawing Fig. 1 diagrammatically shows the whole apparatus, partly in front-elevation and partly in section.
Fig. 2 shows on a larger scaIe the pisten moved by the pressure liquid and the switch connected therewith, in axial section and partly in elevation.
Fig. 3 shows a ground-plan of the switch.
Fig. 4 illustrates diagrammatically the electrical circuits employed in the apparatus.
In the drawing, I indicates a plate working on a hinge 2 and placed in the roadway, for example 30 metres from the corner or turning of the street, and kept in its highest position by means of a spring 3. Under the plate there is placed a pisten 4, on the upper end of which the plate i rests, which piston can be made to move vertically in a cylinder 5. In the cylinder, beneath the pisten, are placed springs 24, which tend to keep the pisten 'in its highest position. The cylinder 5 is connected through a pipe 6 with another cylinder 1, which'likewise contains a vertically movable pisten 8. The cylinders 5 and 'l and the pipe 6 are filled with a liquid.
At the inlet to the cylinder 1 is placed a flapvalve 9 which prevents return-flow of the 'liquid from the cylinder l to the pipe 6. such return flow can take place only'through the by-pass Io, and the resistance to flow through this by-pass can be regulated by means of the adjusting screw 'I I.
The piston 8 is at its upper end provided with an upwards projecting piston-rod l2, the upper end of which bears a cross-piece !3, which is electrically insulated from the piston-rod by means of the insulation 26. The cross-piece [3 bears two arms, rotatable on parallel horizontal axles [4, lt', which are held apart from each other by the pressure of a spring l5. The arms !4, l4' have at their upper ends contact-rollers lE, 16'. Each of the contact-rollers !6, IS' acts together with a set of contact-bars l'l, !8, l! and |1',l8', 19'.
The bars in each set are arranged in succession to each other at the bottom of the guidinggrooves 20, 20', executed in insulating material,
a small space filled with insulating material being interposed between the bars [T and |8 and !8 and IS respectively, and likewise between the bars ll' 'and s' and I 8' and s' respectively.
2| denotes a signal-post provided with a, green light 22 for the "clear-signal and red lights 23 for the stop"-signa1. The clear"-signal 22 is in a circuit embracing the contact-members ll, ll', while the "stop"-signals 23 are in another circut embracing the contact-members 18', IS' on the one side and !8, !9 on the other side. 21 and 28 denote coupling-boxes for the conducting-wires, not shown.
The mode of action of the arrangement is as follows:
In the drawing the apparatus is shown in a. state of rest. The contact-rollers !5, IG' are pipe E and into the cylinder 1. The piston 8 is thereby lifted up and the contact-rollers l6, !6' are raised to the position shown by the stippled v lines in Fig. 2. The circuit for the "clear"-signal is now broken and the circuit for the stop-signal 23 is closed. As soon as the vehicle has passed over the plate I, this is again raised and' the pistons 4 and 8 begin to return to their initial position under the influence of the springs 24 and 25. As already mentioned, the liquid is prevented'by the stop-valve 9 from fiowing back direct from the cylinder 'I to the pipe 6, but must flow through the by-pass l0. The result of this is that the piston 8 and therewith the contact-rollers I 6, Hi' only slowly sink down. The "stop"-signal therefore continues to burn for a certain time, until the contact-rollers come down to the lower ends of the contact-bars [9, IS'. The "stop"-signal is now extinguished, but is immediately after- Wards lighted again when the rollers |6, IS' come into contact withthe bars !8, |8'. These latter are made very short, sothat the stop"-signal is immediately afterwards again extinguished, Whereupon the "clear-signal is lighted.
By means of the adjustment-screw Il the: ac-
tion of the stop"-signa1 can be regulated asdesired. r
Instead of being placed under the plate I as shown in the drawing, the switch may be located overground, for instance in a tightly closed box at the side of the street or road, or possibly in the signal-post.
This latter embodiment involves the advantage crossings or the like wherein a signal device is provided at the crossing and its operation is controlled by an Operating unit mounted to be responsive to traflic approaching the crossing, an Operating unit comprising, a box having a top lid positioned substantially at the level of the street and adapted to be depressed by the passage of a vehicle, a cylinder` and piston unit mounted in operative relationship with respect to said lid whereby the depressing of the' lid causes relative movement between the piston and the cylnder, a fluid-operated switch connected to said cylinder through Conduit means and adapted to be operated by the fluid displaced due to the relative movement of said cylinder and pisten; said switch comprising an upright cylinder having a free inlet valve and an adjustable restricted outlet means and a piston Operating in said cylinder and having rigidly mounted thereon a conducting element, and switch contact means adapted to be bridged by said conducting element.
2. Apparatus as described in claim l wherein said switch contact means comprises two sets of Contacts spaced apart and insulated from 'each other with the result that when the conducting element is in a first position it bridges one set of Contacts and when it is in a second position it bridges the other set of Contacts.
3. Apparatus as described in claim 1 wherein said conducting element is provided with two rollers swingably mounted and spring-pressed toward their respective. 'contact means and wherein said contact means are formed in two parallel opposed g-rooves along which the rollers move.