Vibrating tamper having a single control lever

[0002] Previously known vibrating tampers are equipped with a number of different operating controls, such as a fuel valve, a closable fuel tank venting valve, a throttle control and a switch for stopping the engine. These controls are usually mounted in different positions on the tool and are not always easily accessible. Ease of access is a prerequisite to the safe operation of the vibrating tamper both when using the tool and during transport.

[0003] It is an object of the invention to simplify and make safer the use of vibrating tampers powered by internal combustion engines and designed for compacting clay, sand or gravel, for example in pipe trenches.

[0004] To achieve simple and safe operation of a vibrating tamper, the tool is, in accordance with the invention, equipped with a single control lever with three distinct snap-action positions with the following functions:

[0005] position 1: engine off, fuel valve closed and fuel tank venting valve closed;

[0006] position 2: throttle control in starting/idling position, fuel tank venting valve open and fuel valve open; and,

[0007] position 3: throttle control in full-throttle position, fuel tank venting valve open and fuel valve open.

[0008] The different control lever settings are made distinct by means of a snap-action device which fixes the lever securely in the required position. This is important since the setting of an intermediate position during operation may, for example, damage the centrifugal clutch between the engine and the actual tamping mechanism. Ensuring that the fuel valve is closed when transporting the compactor is important since the tool will often be carried in a random manner. Otherwise, if the fuel valve is open, fuel may run into the engine oil, leading to subsequent engine failure, or leak out through the carburetor.

[0009] For safety reasons, it is essential for the fuel tank venting valve to be closed when transporting the tool to prevent fuel leakage through the venting valve. In the event of an emergency when using the tamper, the engine can be stopped easily by moving the control lever to position 1, in which the fuel supply and fuel tank venting valves are closed automatically.

[0010] The invention will now be described with reference to the drawings wherein:

[0011] FIG. 1 is a perspective view of a vibrating tamper with a control lever mounted integrally on the fuel tank;

[0012] FIGS. 2 to 4 are schematic plan views showing the positions 1 to 3 of the control lever with the cover removed, with FIG. 2 showing position 1 wherein all functions are closed, FIG. 3 showing position 2 which is the starting and idling position and FIG. 4 showing position 3 which is the full-load position;

[0013] FIG. 5 is a schematic vertical section through the fuel tank showing the control lever in position 1;

[0014] FIG. 6 is a similar schematic vertical section with the control lever in position 2 or 3; and,

[0015] FIG. 7 is a schematic of the snap-action device used to releasably fix the control lever in the various positions 1 to 3.

[0016] FIG. 1 shows a vibrating tamper 1 with the control handle 3 and the internal combustion engine 2 which drives the tamper mechanism. The fuel tank is identified by reference numeral 5 and a control lever 4 is mounted integrally on the fuel tank. The cover 6 of the control lever 4 is bolted to the fuel tank.

[0017] FIG. 2 shows the control lever 4, which is free to rotate about its pivot center 8 and is provided with a projecting section 9 with a full-length curved cam slot 10 whose distance from the pivot center 8 decreases continuously as shown. The pivot arm 12 is free to pivot on its journal 13. The free-running pin 11 is attached to pivot arm 12 and runs in the curved cam slot 10.

[0018] The end of the engine throttle cable 14 is seated in a hole 15 on the pivot arm 12 with its sleeve attached to the plate 16. In the position shown, the engine throttle is fully closed and increases to full throttle as the control lever 4 is turned and the other end of the curved cam slot 10 is reached. The outer end of the pivot arm 12 is provided with a projection 17 which, in the position shown, actuates a microswitch 18 which short-circuits the engine ignition circuit. In the case of a diesel engine, the engine is stopped in the position shown since the throttle is fully closed. The fuel tank filler pipe is identified by reference numeral 19 and the internally threaded bosses 20 are provided for bolting the cover 6 of the control lever 4 into position.

[0019] FIG. 3 shows the control lever in the starting and idling position. In this position, the pivot arm 12 has been actuated by the movement of the curved cam slot thereby pulling the throttle cable into the starting/idling position in which the projection 17 on the pivot arm 12 no longer operates the microswitch 18.

[0020] FIG. 4 shows the control lever 4 in the full-throttle position, which is reached when the control lever has been moved to its end position, at which the pin 11 acting in the curved cam slot 10 has pivotally moved the pivot arm 12 so that the throttle cable 14 is pulled out to its full-throttle position. The microswitch 18 remains unactuated.

[0021] FIG. 5 is a schematic vertical section through the fuel tank 5 and control lever cover 6 when the control lever 4 is in position 1 shown in FIG. 2. FIG. 5 shows a valve spindle 21, which is held against the tank vent opening 23, by the upward force of the spring 22 so that the shoulder 24 on the spindle and O-ring 25 seal the opening. The lower section of the valve spindle runs freely in a cylindrical valve sleeve 27 without bottoming in the sleeve. The valve sleeve 27 is provided with a collar 40 which is acted upon by the spring 29 to seal the outlet opening 30 in the tank 5 by pressing an O-ring 28 against the opening. The upper section 21 of the valve spindle runs through the tank vent opening 23 to act on a ball 31, which is free to move in a cylindrical sleeve 32 on the top of the tank and, in certain positions, is acted on by the underside of the control lever 4. The control lever 4 does not act on the ball 31 in the position shown, with the result that both the tank outlet and vent are closed. An air filter 26 is fitted in the control lever cover 6.

[0022] FIG. 6 is a schematic vertical section through the fuel tank 5 and control lever cover 6 when the control lever 4 is in position 2 or 3. FIG. 6 shows that the chamfered surface 33 on the control lever 4 has pressed the ball 31 downward with the result that the valve spindle 21 has been forced downward, first opening the tank vent 23 and, when the lower end portion 38 of the spindle has bottomed in the valve sleeve 27, opening the outlet 30 of the fuel tank 5. By making the spring 22 weaker than the spring 29, the tank vent is opened before the fuel tank outlet 30. The fuel supply line to the engine is connected to the pipe stub 34 in a conventional manner.

[0023] FIG. 7 is a schematic view of a ball-type snap-action detent device 35 which serves to releasably fix the control lever 4 in its different positions by pressing a ball 36 into hemispherical recesses 37 located in the control lever so as to correspond to the engine off, starting/idling and full-throttle positions. FIG. 7 shows the ball in the starting/idling position.

[0024] The invention simplifies and makes safer the use of vibrating tampers 1 powered by internal combustion engines and designed for compacting clay, sand and gravel, for example, in pipe trenches.

[0025] The invention is not limited to the embodiment described, but can also be applied to other internal combustion engine-powered machines or tools, such as vibrating compactors.

[0026] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.