EP1281659A1

EP1281659A1 - Scissor lift with retractable wheels

Info

Publication number: EP1281659A1
Application number: EP02016194A
Authority: EP
Inventors: Mauro Donati
Original assignee: Bolzoni SpA
Current assignee: Bolzoni SpA
Priority date: 2001-08-03
Filing date: 2002-07-22
Publication date: 2003-02-05
Also published as: ITMI20011722A0; ITMI20011722A1

Abstract

A pantograph elevator platform (10) comprises a base (11) designed to rest on the ground during use and from which a kinematic pantograph mechanism (23) rises, which mechanism is operable for lifting of a loading flatbed (12) from the base. The platform (10) comprises wheel assemblies (21, 22) that are susceptible of engagement in the kinematic mechanism to drivingly lift the base (11) from the ground when the loading flatbed is moved with respect to the base thereby enabling displacement thereof. Advantageously, the wheel assemblies are fully removable from the base when not in use.

Description

The present invention relates to a pantograph elevator platform of a type merely resting on the ground, provided with devises enabling lifting of the platform on wheels through operation of the pantograph to enable displacement of the platform.
Use of pantograph elevator platforms of small capacity and in particular of reduced thickness often contemplates their mere resting on the ground, without pits for receiving the base and the kinematic mechanism being required. Since these platforms do not require particular environment equipping, they are likely to be transferred to different use places. For instance, in the case of platforms of unfrequent use, instead of having as many platforms as the places where they are to be employed, availability of a reduced number of platforms is preferred and they are moved from one place to another depending on current requirements. However tackles or lifts for transportation of same are not always available.
Platforms permanently resting on wheels would solve the problem, but they would fall in the category of movable bridges and therefore would be subjected to severe regulations in terms of manufacture, control and servicing. Transportation devices have been proposed in the known art which comprise fixed wheels to be disposed on one side of the platform and a drawbar with wheels and lifting hook to be fitted on the other side. In use these devices must be hooked to the platform, and the drawbar must be manually lowered to cause a thrust from the ground for lifting of the whole platform. The drawbar must then be forcedly maintained to a lowered position during the whole travel. Therefore a great effort is required by this system for the purpose of combining the continuous manual lifting action with the thrust action for displacement and it is therefore only suitable for very small and light-in-weight platforms. In addition, since two simultaneous actions (a lifting and a driving action) are required by the system, the system itself does not ensure the necessary safety for the operator. On the other hand, should powered lifting devices be added, cost would become too high, also taking into account the limited use to be done of same in platforms that are generally substantially permanent in place.
It is a general aim of the present invention to obviate the above mentioned drawbacks by providing a platform that is provided with devices enabling easy and comfortable self-lifting when necessary, without the addition of expensive powered mechanisms being required.
In view of the above aim, in accordance with the invention, a pantograph elevator platform has been conceived which comprises a base designed to rest on the ground during use and from which a kinematic pantograph mechanism rises, which mechanism is operable for lifting of a loading flatbed from the base, characterised in that it comprises wheel assemblies that are susceptible of engagement in said kinematic mechanism to drivingly lift said base from the ground upon movement of the loading flatbed with respect to the base thereby enabling displacement thereof.
For better explaining the innovative principles of the present invention and the advantages it offers over the known art, a possible embodiment applying the above principles will be described hereinafter by way of example, with the aid of the accompanying drawings. In the drawings :

Fig. 1 is a diagrammatic side view of the platform in accordance with the invention;
Fig. 2 is a plan view of the elevator platform in a lowered position and devoid of the upper loading flatbed.

With reference to the drawings, a pantograph elevator platform generally identified by 10 is shown. In Fig. 1 the platform can be seen in a raised position.
The platform comprises a base 11 designed to rest on the ground during use and from which a kinematic pantograph mechanism 23 rises which is operable to lift a loading flatbed 12 from the base.
The kinematic mechanism 23 comprises a first and a second pantograph portions consisting of arms 13, 14 articulated on each other in an intermediate position at 15 and having an end 16, 17 pivotally mounted on the loading flatbed and the base respectively and the opposite end 18, 19 sliding along the loading flatbed and base, respectively.
Actuators 20 control movement of the kinematic mechanism for lifting and lowering of the loading flatbed.
Platform 10 comprises wheel assemblies 21, 22 that can be engaged in said kinematic mechanism 23 to drivingly lift the base 11 from the ground upon movement of the loading flatbed relative to the base and enable displacement thereof.
Advantageously, the insertable wheel assemblies are completely removable from the platform when not in use.
The first wheel assemblies 22 each comprise an arm 24 to which a wheel 25 is pivotally mounted, said wheel being received in a removable manner in an appropriate seat 26 formed in the arm 14 of the kinematic pantograph mechanism to substantially constitute an extension thereof out of the base platform. In this way, when the kinematic pantograph mechanism is driven, the wheel 25 is brought into contact with the ground and the platform is raised from that side, as clearly shown in Fig. 1. The seat 26 can be a mere square sleeve welded to the side of arm 14. A clip 28 (a spring clip, for example) may be also provided to prevent accidental slipping off of arm 24 from seat 26.
A second wheel assembly 21 comprises an arm 27 on which a wheel 29 is pivotally mounted at one end thereof. This arm 27 is pivotally mounted to the base at an intermediate position, at 30, and has the other end 31 slidably resting on a portion of the kinematic pantograph mechanism for rotation about its pivoting point upon movement of the kinematic mechanism. In this way, wheel 29 comes into contact with the ground and raises the platform from the ground when the kinematic pantograph mechanism is driven.
This second wheel assembly is advantageously disposed on the side of the kinematic pantograph mechanism portion which is slidable on the base and the support arm 27 of the wheel grows longer to slidably rest on a crosspiece 34 of that portion of the pantograph kinematic mechanism, as clearly shown in Fig. 2.
Advantageously, the arm of the second wheel assembly is removably mounted on the pivoting point (as viewed from Fig. 2) so that it can be slipped off and removed when not in use. Alternatively, arm 27 can contemplate other means for disengagement from the kinematic mechanism while keeping the wheel assembly mounted thereon. For example, arm 27 can be of the folding type and can be bent at an intermediate position after unlocking of a bolt, or the arm can be also pivotally mounted according to a vertical axis 32 so as to rotate sideways until coming out of the interference region with the kinematic mechanism. To ensure a correct positioning of arm 27 during use, side guide elements 33 may be provided on the crosspiece 34.
At this point it is apparent that the intended purposes have been reached, by providing a platform on which devices for self-lifting of the whole platform from the ground are mounted, which are operated, when wished, by the same kinematic lifting mechanism of the loading flatbed. All that in a simple, safe and cheap manner.
Obviously, the above description of an embodiment applying the innovative principles of the present invention is given by way of example only and therefore must not be considered as a limitation of the scope of the invention as herein claimed. For example, some wheel assemblies (the rear assemblies, for example) may be provided not to be movable for lifting of the platform, or all the wheel assemblies may be conceived as being identical with each other. In addition, the wheel assemblies such as 22 may be provided to be overturned when in a non-use position instead of being slipped off.

Claims

A pantograph elevator platform comprising a base designed to rest on the ground during use and from which a kinematic pantograph mechanism rises, which kinematic mechanism is operable for lifting of a loading flatbed from the base, characterised in that it comprises wheel assemblies that are susceptible of engagement in said kinematic mechanism to drivingly lift said base from the ground upon movement of the loading flatbed with respect to the base and enable displacement thereof.
A platform according to claim 1, characterised in that the wheel assemblies susceptible of engagement in said kinematic mechanism can be removed from the platform when not in use.
A platform according to claim 1, characterised in that first wheel assemblies comprise an arm to which a wheel is pivotally mounted which is removably inserted in an appropriate seat on an arm of the kinematic pantograph mechanism to substantially form an extension thereof out of the base platform, so as to bring the wheel to lift the platform from the ground when the kinematic pantograph mechanism is driven.
A platform according to claim 1, characterised in that the second wheel assemblies comprise an arm to which a wheel is pivotally mounted at an end thereof, this arm being articulated on the base at an intermediate position and having the other end resting on a portion of the kinematic pantograph mechanism for rotation about its pivoting point upon movement of the kinematic mechanism, so as to bring the wheel to lift the platform from the ground when the kinematic pantograph mechanism is driven.
A platform according to claim 4, characterised in that the arm of the second wheel assembly is removably mounted on the pivoting point so that it can be removed when not in use.
A platform according to claim 3 or 4, characterised in that on one side the base comprises a pair of first wheel assemblies disposed in side by side relationship and on the other side the base comprises a second wheel assembly disposed centrally with respect to said other side.
A platform according to claim 6, characterised in that the second wheel assembly is disposed laterally on a portion of the kinematic pantograph mechanism which is slidable along the base, the wheel-supporting arm growing longer so as to slidably rest on a crosspiece of this portion of the kinematic pantograph mechanism.