Service car for storing and marking available tools

A service car for storing and making available tools, accessories and the like comprises a travelling base. At least one column extends upwards from said travelling base. At least one platform is vertically movable along the column. A balancing gas spring is provided within the column. This balancing gas spring acts onto the platform opposite to the action of gravity.

BACKGROUND OF THE INVENTION 
Service cars are frequently used in factories and in repair shops. The 
service cars can be closed and are used in closed condition for storing 
tools. The service cars are opened in that two or more platforms or trays 
are vertically moved along columns. The platforms or trays can be secured 
in various heights. These platforms or trays can be used for carrying 
tools. 
STATEMENT OF THE PRIOR ART 
In known service cars the platforms or trays are elevated solely by manual 
force. Due to their own weight and due to the weight of the tools carried 
thereon considerable manual forces are necessary for lifting and securing 
the platforms or trays. 
OBJECT OF THE INVENTION 
It is an object of the present invention to provide a service car which can 
be opened and closed with reduced manual force. 
SUMMARY OF THE INVENTION 
A service car for storing and making available tools, accessories and the 
like comprises a travelling base. At least one column extends upwards from 
said travelling base. At least one platform is vertically movable along 
said at least one column. Balancing means are provided within said at 
least one column. These balancing means act onto the platform opposite to 
the action of gravity. 
By the balancing means at least part of the weight of the platform is 
counter-balanced so that a reduced manual force is necessary for 
vertically moving the platform. 
One tries to adapt the balancing action of the balancing means exactly to 
the weight of the platform. As, however, the weight of the tools lying on 
the platform varies, one must consider the possibility of deviations from 
the balanced condition. This means that one is either obliged to assist 
upward movement by manual force or to overcome the balancing means in 
downward direction by manual force. 
If the balancing means are selected such that their lifting action 
overcomes the weight of the platform and the goods lying thereon, the 
upper end position of the platform is obtained by the balancing means, on 
the one hand, and by abutment means, on the other hand. In this case the 
lowermost position of the platform must be secured by securing means. If 
the balancing action is smaller than the maximum weight of the platform 
and the tools, securing means are also necessary, which maintain the 
platform in the elevated position. 
In order to completely enclose the tools, the travelling base is formed as 
a container having a base wall, a side wall and an upper opening defined 
by said side wall such that the platform or platforms are at least 
partially receivable by the container through the opening. 
In order to easily move the service car on ground, the travelling base can 
be provided with a plurality of travelling wheels. 
In order to move the service car in varying directions, at least part of 
the travelling wheels can be castor wheels. 
In order to stabilize the platform and prevent tilting of the platform, the 
travelling base is provided with an elongate horizontal axis and two 
columns are provided adjacent to respective ends of the elongate 
horizontal axis. 
In case the travelling base is provided with a side wall, a plurality of 
columns may be provided inside said side wall. 
In order to provide a large number of tools in readily accessible 
condition, a plurality of platforms are located one above the other. The 
balancing means engage an upper one of said plurality of platforms and at 
least one lower platform is suspended at said upper platform by flexible 
suspension means. Such the movement of a plurality of platforms is 
synchronized. 
In case of a plurality of platforms, securing means may be provided for 
securing said upper platform in at least one position along said at least 
one column. If the balancing action overcomes the weight of all platforms, 
the securing means are necessary to maintain the platforms in their 
lowermost position. If, on the other hand, the balancing means are 
insufficient for overcoming the weight of the platforms, the securing 
means are needed for maintaining the platforms in the elevated position. 
A cover member may be movable along said at least one column above said at 
least one platform. It is possible that the balancing means act onto the 
cover member and that at least one platform is suspended at the cover 
member by flexible suspension means. In such case the cover member may be 
provided with securing means for securing it in at least one position 
along said at least one column. 
As however the cover member is of relatively low weight, it is preferable 
that even in case of provision of a cover member the balancing means act 
onto said at least one platform. Even then said at least one platform may 
be suspended at said cover member by flexible suspension means and 
securing means may be provided on said cover member for securing said 
cover member in at least one position along said at least one column. Such 
the necessary stroke of the balancing means is reduced and nevertheless 
the cover member and the platform or platforms may be brought to elevated 
positions by one action. 
According to a preferred embodiment the travelling base is a container 
having a base plate with an elongate axis and a side wall. Two columns 
extend upwards from said base plate within said side wall in substantially 
vertical direction. A plurality of platforms is vertically guided on the 
columns one above the other. Balancing means are provided in each of the 
columns. The balancing means act onto the uppermost of the platforms. At 
least one lower platform is suspended at the uppermost platform by 
flexible suspension means. A cover member is guided on the columns above 
the uppermost of the platforms. The cover member is provided with securing 
means for securing it in at least one position along the columns. The 
uppermost platform is suspended at the cover member by flexible suspension 
means. The cover member may be secured in its uppermost position. The 
elevated position of the platforms may be secured through the various 
groups of flexible suspension means even if the balancing means are not 
sufficient to overcome the gravity of all platforms. On the other hand, 
the cover member may be secured in its lowermost or closing position so 
that all platforms are maintained within the container even if the weight 
of the loaded platforms is not sufficient to overcome the balancing force 
of the balancing means. 
The platforms may be shaped as trays or otherwise shaped such as to 
maintain the tools in good order. Even the cover member may be used for 
carrying tools during operation. 
In order to transmit the balancing action of the balancing means to the 
respective platform or cover member, said at least one column may be 
provided with at least one substantially vertical slot and said balancing 
means may be provided with at least one lateral engagement arm which 
engages one of said platform and a cover member. 
While the balancing means may be also mechanical springs, it is preferred 
that said balancing means comprise at least one gas spring. The gas spring 
may be of the well known type having a cylinder member with a cavity 
therein, a volume of pressurized gas being provided within said cavity and 
a piston rod extending through one end of said cylinder. An outer end of 
said piston rod may be fixed to one of said travelling base and said at 
least one column. The cylinder member may be in balancing connection with 
said at least one platform. 
The main advantage of such a gas spring is that it is adapted in its 
natural shape to the shape of a column. A further advantage is that the 
balancing force of the gas spring does not considerably vary in response 
to inward and outward movement of the piston rod. This is particularly 
true if the cross-sectional area of the piston rod is small as compared 
with the cross-sectional area of the cavity. 
In order to adapt readily accessible gas springs to the shape of the 
column, the cylinder member is surrounded by a spacer unit, said spacer 
unit being guided within said at least one column. This spacer unit may be 
provided with at least one laterally extending engagement arm which passes 
through a slot of said column and is in load-transmitting connection with 
said at least one platform. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its use, reference 
should be had to the accompanying drawings and descriptive matter in which 
there is illustrated and described a preferred embodiment of the invention 
.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The service car of FIG. 1 is designated by 10. It comprises a container 11 
with a base plate 11a and a side wall 11b. An upwards directed opening 11c 
is defined by the side wall 11b. The base plate 11a is provided with 
travelling wheels 40, at least two of these travelling wheels being castor 
wheels and being provided with a brake 42. Two substantially vertical 
columns 15 are fixed to the base plate 11a inside the side wall 16. On the 
columns 15 there are guided two platforms 12 and 13 and a cover member 43. 
The platforms 12 and 13 can be completely lowered into the container 11 
through the opening 11c such that the cover member 43 can close the 
opening 11c. The cover member 43 is provided with a securing bolt 45 which 
is shown in more detail in FIG. 4. This securing element 45 can be 
operated by hand and is biased by a spring 46 towards engagement with a 
column 15. The column 15 is provided with one securing recess 47 
corresponding to the most elevated position of the cover member 43 as 
shown in FIG. 1. A further securing recess 48 is provided on the column 15 
in a position corresponding to the closing position of the cover member 43 
with respect to the container 11. 
The upper platform 13 is suspended at the cover member 43 by chains 16a, 
whereas the lower platform 12 is suspended at the platform 13 by chains 
16. In FIG. 1 the cover member 43 is secured at the columns 15 by the 
securing bolt 45. A similar securing bolt may be provided at the left-hand 
end of the cover member 43, as seen in FIG. 1. The platform 13 is 
suspended by the chains 16a and the platform 12 is suspended at the 
platform 13 by the chains 16. 
According to FIG. 2 a gas spring 18 is provided within each column 15. The 
gas spring 18 comprises a cylinder 19 and a piston rod 21. The downwardly 
directed piston rod 21 is fixed by its lower end 26 to a support member 25 
which is secured with respect to the column 15 and/or the base plate 11a. 
The cylinder member 19 is housed within a spacer unit 24 which is 
slidingly guided within the column 15. The spacer unit 24 is closed at its 
upper end by a cover plate 29. This cover plate 29 is provided with a bore 
30 having thread means 31. Lateral engagement arms 23 are threadedly fixed 
to the spacer unit 24 and pass through slots 22 of the column 15. These 
lateral engagement arms 23 engage the upper platform 13 at the lower side 
thereof. 
The gas spring 18 is shown in more detail in FIG. 3. The piston rod 21 is 
provided with a piston 50 inside the cavity 51 of the cylinder member 19. 
The cavity 51 is subdivided by the piston 50 into two working chambers 51a 
and 51b. The two working chambers 51a and 51b are interconnected by a bore 
52 extending through the piston 50. The cavity 51 is sealed by a first 
group of sealing means 53 and a second group of sealing means 54. An oil 
chamber 55 is provided between the sealing means 53 and 54. Pressurized 
gas is contained within both working chambers 51a and 51b. The piston rod 
21 is biased by the pressurized gas in downward direction. Movement of the 
piston rod member 21 with respect to the cylinder member 19 is damped by 
the reduced cross-section of the bore 52. 
According to FIG. 2 the piston rod member 21 is stationary and the cylinder 
member 19 is axially movable with respect to the piston rod 21. Due to the 
pressurized gas within the cavity 51 the cylinder member 19 is biased 
upwards in FIG. 2. The upwards directed force acting onto the cylinder 
member 19 is transmitted through the spacer unit 24 and the engagement 
arms 23 to the upper platform 13 in FIG. 1. It is assumed now that the 
upwards directed force of the gas springs is sufficient to overcome the 
weight of the loaded platforms 12 and 13. When the cover member 43 is 
closed and secured in closed condition with respect to the container 11 by 
the securing bolts 45 engaging the securing recesses 48, the platforms 12 
and 13 are retained within the container 11. When the securing bolts 45 
are withdrawn the gas springs 18 lift the platform 13 up to the position 
shown in FIG. 1. This position is defined by the engagement arms 23 
abutting the upper ends of the slots 22. During the upward movement of the 
platform 13 the chains 16 are straightened. After the chains 16 have been 
straightened, the lower platform is lifted by the upper platform 13 
through the chains 16 up to the position of FIG. 1. The cover member 43 is 
to be lifted by hand into the position shown in FIG. 1 and is then secured 
by the securing bolts 45 engaging the recesses 47. The cover member 43 may 
be lifted by the platform 13 up to the upper position of the platform 13 
so that it must be manually lifted only for the remainder of the path 
between the position of the platform 13, as seen in FIG. 1, and the 
position of the cover member 43, as seen in FIG. 1. 
If the force of the gas spring is not sufficient to overcome the weight of 
the platforms 13 and 12 and the weight of the cover member 43, the upward 
movement of the cover member 43 must be manually assisted. This manual 
force acting onto the cover member 43 is transmitted to the platform 13 
and the platform 12 after the chains 16a and 16, respectively, have been 
straightened. Even if manual assistance is necessary for lifting the cover 
member 43, the platform 13 and the platform 12, the necessary force for 
lifting this components is reduced due to the presence of the gas springs. 
It is to be understood that the gas spring may also engage by its 
engagement arms 23 the cover member 43. In this case even manual lifting 
of the cover member is avoided if the spring force of the gas springs is 
sufficient to lift the cover member 43, the platform 13 and the platform 
12 one after the other. 
As can be seen form FIG. 2, the upper ends of the columns 15 are provided 
with spherical knobs 17. These spherical knobs 17 are intended for the 
operator to move the service car on ground. 
The threaded bore 30 in the cover plate 29 is provided for assisting 
insertion of the spacer unit 24 and the gas spring 18 into the column 15. 
Tools, accessories and the like may be positioned on the platforms 12 and 
13 and on the bottom of the container 11. During operation additionally 
tools may be positioned on the top side of the cover member 43. 
While specific embodiments of the invention have been shown and described 
in detail to illustrate the application of the inventive principles, it 
will be understood that the invention may be embodied otherwise without 
departing from such principles. 
The reference numerals in the claims are only used for facilitating the 
understanding and are by no means restrictive.