NL8801732A - JACK WITH STAGE ORDERING, SIMULTANEOUSLY TELESCOPIC HYDRAULIC JACKS. - Google Patents

Description

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Jack with graduated, simultaneously operated telescopic hydraulic jack parts

Description

The Italian patent no. 1000659, in the name of the applicant, relates to telescopic hydraulic multi-stage jacks, which are constructed in such a way that the different hydraulic steps can be put in or out of operation at the same time, whereby a minimum amount of time is required for expansion and / or withdraw the whole.

The said telescopic jack, mounted on wagons, makes it possible to carry out quick operations at considerable heights, which can be achieved by means of a platform mounted on the telescopic end element. The platform can support one or two operators and associated equipment for repairs, rescues and / or various other operations where / similar devices cannot be used due to their larger size and the time required to deploy them.

These hydraulic jacks have the drawback that during the retraction phase the telescopic elements of the cylinder-piston assemblies, which form the device, cannot always reach the fully retracted position.

20 It has been found that a limited amount of hydraulic fluid remains between the outer base of each piston and the inner base of the corresponding cylinder, due to the leakage of oil past the sealing rings, which occurs when the operating pressure of the pump or pumps is low 25 when approaching the fully retracted position through the jack.

This phenomenon does not prevent the operation of the device, but a variation in the overall length of the device could cause transportation problems, assuming that the unit is mounted on a carriage with a bed length calculated to the length that the would have furnishing when all its elements are completely withdrawn.

The object of the invention is to overcome the aforementioned .8801732-2 -v shortcoming, which is accomplished by equipping each cylinder piston assembly with a check valve. The check valves are opened by the pressure of the hydraulic fluid when the cylinders are expanding; the valves 5 are closed during the retraction phase, but when the cylinders have almost reached the fully retracted position, the valve provided on each cylinder is opened automatically, thanks to the intervention of a projection which is integral with the surface of the inner base of the cylinder. corresponding cylinder, whereby the fluid contained in each cylinder is completely expelled. The fluid is transported to the reservoir, allowing all telescopic elements to return to the correct fully retracted position.

The invention will now be further described by way of example 15 with reference to the accompanying drawings, in which: figure 1 is a partly cut-away view of the jack according to the invention, the telescopic elements floating in the fully retracted position; Figure 2, similar to Figure 1, illustrates the jack in an intermediate expanding or retracting position; Figure 3 is a multi-scale axial exploded view of one of the check valves that control the passage of hydraulic fluid during the expansion phase of the device 25 and are automatically opened during the final phase of retraction to drive away any residual fluid; figure 4 schematically illustrates on a different scale a possible version of the jack with five hydraulic steps.

Taking into account that the shape, length and number of elements may vary in each version of the hydraulic jack, depending on the purpose for which the jack will be used, the drawings described below are intended only to illustrate the operation of the device clarify.

In Figures 1, 2 and 3, arrows X show the direction of flow of the hydraulic fluid under pressure, which fluid is pumped through a series of valves reaching cylinder 2 (Figure 2). The various cylinder-suction assemblies which form the whole - indicated by reference numerals 3, 4, 5 and 6 respectively - are provided with .8801732 ψ '* -3- sealing rings 7 and at least one non-return valve A, shown in detail in figure 6. The pressurized fluid arriving from X enters cylinder 2, opening valve A (see the position shown by the broken lines in Figure 3). The fluid also flows through radial passages 8, entering the various telescopic elements 2 to 6. The jack moves from the position illustrated in Figure 1 to the intermediate positions - one of which is shown in Figure 2 - until it reaches the fully expanded position, which is schematically illustrated in figure 4. A valve is located at the locations shown by Z and is coupled to the pumping system (not illustrated).

When the jack is to be transferred from the fully deployed position shown in Figure 4, or any other position between the fully deployed and fully retracted positions, to the fully retracted position, the direction of the hydraulic fluid must be reversed. The fluid passes through orifice 9 and through passages 8, following the path indicated by arrows Y, which passages at this point serve as passages 20 for the discharge of hydraulic fluid returned to the system reservoir. The check valves A remain closed during this operating phase.

When the jack arrives at the almost fully retracted position (example shown in Figure 2), some of the fluid may tend to remain in the chambers indicated by B in Figure 2, due to changes in the working conditions of the jack.

Thanks to the present invention, this drawback is eliminated during the last stage of retraction (see the position shown in Figure 2), when the various cylinder piston assemblies protrude shafts 10 (Figure 3) from each valve A associated with the base of the different elements. in contact with the elements underneath, opening the valves A and allowing complete removal of hydraulic fluid from the interior of the chambers B.

Under these conditions, the retraction of the various steps of the telescoping jack is complete? the various elements have returned to the position shown diagrammatically in Figure 1.8801732 Λ »Λ -4-.

Figure 3 shows springs 12 and 13 which counteract the movement of ball 14. The springs are suitably calibrated to meet the operating pressures used.

Furthermore, assuming that valve 10 can always be opened automatically as described above, valve 10 may have any suitable construction different from that shown as an example.

10 In the attached drawings are the valves

Pi is shown as aligned in axial direction and each valve has a minor top protrusion intended to collide with Appendix 10 of the valve above. The invention includes valves with different locations and structures.

.8801732

Claims (3)

Jack with stepped and coaxially arranged hydraulic jack parts, which are telescopic and expandable simultaneously, comprising a number of cylinder-piston assemblies which are connected to each other by inner radial passages, the basic cylinder and the end cylinder being provided of openings, respectively connected to the hydraulic circuit controlled by a control unit and a reversible pump, characterized in that each cylinder-piston assembly (3, 4, 5, 6), with the exception of the basic cylinder-piston-10 assembly (2), provided with at least one non-return valve (A), which is opened automatically during the jack-off phase of the jack and remains closed during the initial jack-in-jack phase, and which is equipped with an appendage (10) , which opens automatically during the final phase of retraction, allowing the hydraulic fluid to be completely discharged so that the jack is r the minimum retracted height can return. Jack according to claim 1, characterized in that each said valve (A) is provided with a tag (10) protruding from the bottom surface of the corresponding base of the associated cylinder-piston assembly, the tag (10) base of the corresponding cylinder engages during the final stages of retraction so that the valve is opened against the reaction of elastic devices, allowing the remaining hydraulic fluid to be completely discharged. Jack according to claim 1 or 2, characterized in that said valves (A) are ball valves comprising a shaft (10) protruding from the valve housing, relative to the base of the corresponding cylinder-piston assemblies - 30 set. -8801732 * -6- rectify shortcoming. This is accomplished by equipping each cylinder-piston assembly with a check valve. The check valves are opened by the pressure of the hydraulic fluid when the cylinders are expanding; the valves are closed during the retraction phase, but when the cylinders have almost reached the fully retracted position, the valve provided on each cylinder is opened automatically, thanks to the intervention of a projection integral with the surface of the inner base of the corresponding cylinder, making it in every cylinder * 8801732