FIELD OF THE INVENTION
The present invention relates to a system for servicing/maintenance of trailing cable
carrier trolley in overhead cranes. More particularly, the present invention is directed to
providing a simple and user friendly tool in the form of an adjustable lifting tackle for
servicing of trailing cable carrier trolley in overhead cranes or for replacement of
wheels/parts thereof in a faster and safe manner using less manpower.
BACKGROUND OF THE INVENTION
Cranes are essential and important equipment used in industry for transporting and/or
loading of heavy material in day to day work. Different types of cranes are used in
industry out of which Electrical Overhead Traveling cranes (EOT) are most extensively
used for operation and maintenance purposes. In a plate mill of a steel plant, plates
can only be transported and loaded with the help of magnetic hoisting cranes. These
cranes are also used in maintenance of plant and machinery.
In any crane, the movement of trolley and hoist are generally achieved through bus
bar or cable connections. They are used to carry power from the panel. The earlier
design of cranes used only copper bus bars. As they involved copper conductor and
current collectors used to collect current from bus bar, hence maintenance requirement
of these cranes are very frequent, complicated and costly. To solve this problem, these
cranes were converted to trailing cable type power supply system which is a better
system requiring less maintenance. The reliability of these cranes depends on design of
trailing cable system and design of cable trolley. However, wheels of cable carriers are
subjected to wear and tear depending on load and rate of use. Maintenance of trailing
cable trolley is very difficult because of their position on the cranes. This becomes
more difficult in converted (from bus bar to trailing cable type) cranes because of
constraints in converted design. Working platform in these cranes plays an important
role. The weight of trailing cable carrier is at least 30 kg supported in I beam. To
replace a worn out wheel of the cable carrier trolley in the conventional practice,
following steps are followed:
Step I: Whole cable carrier is to be lifted slightly and to be tied with rope from I beam
or roof structure support.
Step II: Both the stud fixing the cable Decker with carrier are to be made loose and the
side nuts are loosened on both sides of studs and both nuts are removed on one side
of studs.
Step III: The parts fixing the wheel on carrier including side plates are removed and
the defective wheel is taken out.
Step IV: New wheel replacing the defective one is placed in position.
Step V: Assemble the cable trolley as it was before tightening all parts/nuts/stud that
were loosened and remove the rope and then test for smooth travel of the trolley.
Time required to carry out the above steps depends on skill level and experience of the
personnel involved. Usually l-2hr is required to replace one wheel/wheels in one
trolley. However, the time required multiplies with number of wheel/s to be replaced in
number of trolleys. Following problems are experienced in general during trolley
maintenance/wheel replacement as per conventional practice:
a. When the height of I beam exceeds 2 meter, it is difficult and unsafe to work
because of approach problem to the trolley.
b. Since the weight of trolley plus the weight of cables is more than 100kg, it
requires more persons/workmen to carry out the maintenance/wheel
replacement job.
c. There is chance of finger/hand getting entangled and pressed when the rope is
tied on the I beam or fixed structure because of weight of cable trolley.
d. The entire process is manual and time consuming.
e. Production and productivity is adversely affected due to longer down time.
f. When I beam is located out side the crane, the approach problem is more
critical and arrangement of additional scaffolding to enable approach to cable
carrier.
g. Higher cost more time and manpower needed for maintenance /replacement of
cable trolley parts.
There has been thus a need in the art to developing an effective fixture/tool to solve
the above stated problems and limitations in the conventional maintenance of cable
carrier trolley in overhead cranes to ensure repair/replacement in a cost effective,
faster and safe manner requiring less manpower with required skill level thus reducing
the down time and improving productivity of plants.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to providing a tool for
maintenance of trailing cable carrier trolley for replacement of worn out wheels in
overhead cranes in less time and with less manpower in faster and safe manner.
A further object of the present invention is directed to providing a tool for maintenance
of trailing cable carrier for replacement of wheels in overhead cranes wherein the
Decker for trailing cable support can be lifted with said adjustable tool supported on I
beam so that weight of any number of cable with the carrier is no constraint.
Yet another object of the present invention is directed to providing a tool for
maintenance of trailing cable carrier for replacement of wheels in overhead cranes
wherein approach problem particularly in converted cranes for maintenance persons
eliminated as only one person can do the wheel replacement job using the tool.
A still further object of the present invention is directed to providing a tool for
maintenance of trailing cable carrier for replacement of wheels in overhead cranes
wherein while replacing the parts of the cable trolley, the cables need not be removed
during the application of the tool.
A still further object of the present invention is directed to providing a tool for
maintenance of trailing cable carrier for replacement of wheels in overhead cranes
wherein additional scaffolding to enable approach to cable carrier will not be required.
A still further object of the present invention is directed to providing a tool for
maintenance of trailing cable carrier for replacement of wheels in overhead cranes
wherein use of rope for tying the cable carrier for lifting will not be required thus
avoiding possibility of pressing of finger or hand of personnel.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a system for replacement of
spares in trailing cable carrier trolley in overhead cranes, comprising
a c-channel;
a pair of hook means spaced apart and supported with respect to said C-channel;
said hook means secured with respect to said C-channel such as to enable lifting of the
cable carrier when hooked thereto by means adapted to release and retract the vertical
height of the respective hooks from said C-channel.
Another aspect of the present invention is directed to said system for replacement of
spares in trailing cable carrier trolley in overhead cranes comprising
said c-channel;
said pair of hooks having threaded and nut fixed at each of said c-channel through
drilled holes facilitating said release and retract the vertical height of the respective
hooks from said C-channel for lifting of cable trolley for replacing parts;
a sling chain of suitable length with a V hook welded at the bottom end is suspended
from each threaded hook for gripping the cable decker below the carrier trolley prior to
lifting.
A further aspect of the present invention is directed to said tool for replacement of
spares in trailing cable carrier trolley wherein said C-channel is of size
100x50x5mmthick and 500mm long.
A still further aspect of the present invention is directed to said tool for replacement of
spares in trailing cable carrier trolley wherein said threaded hook with nut is 10 mm in
dia and 200 mm long.
A still further aspect of the present invention is directed to said tool for replacement of
spares in trailing cable carrier trolley wherein each said sling chain is 6mm chain
assembly of 300 mm length with said V shaped hook welded at bottom end made of
chain is made of MS flat of size 30mmwide x 5mm thick.
According to yet another aspect of the present invention is directed to a method for
replacement of spares in trailing cable carrier trolley in overhead cranes using the tool
as described above comprises the steps of:
(i) Placing the tool for replacing cable carrier crosswise on the I-beam just over
the defective trolley to be repaired/replaced with spares;
(ii) Positioning both the V shape hook of chain link attached to threaded hook
just below the semicircular decker(meant for cable support) with cables laid
therethrough, so as to grip the decker from two sides;
(iii) tightening nuts of both the threaded hooks in such a way that the cable
trolley get loose over the I-beam so that the total load of the cable trolley
get transmitted to the tool;
(iv) loosening and removing the studs, nuts and side plates to remove the
parts/wheel to be replaced;
(v) remove worn out parts/wheel and replacing with new /good spare/wheel ;
(vi) tightening the studs and nuts after placing the side plates after
repair/replacement of spare/wheel;
(vii) releasing the load on the tool by loosening the nuts of the threaded hook
(viii) removing the tool from the position and check for satisfactory operation of
the cable carrier trolley with replaced parts.
The objects and advantages of the present invention are described in greater details
with reference to the following accompanying nonlimiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 a & 1 b: shows the general arrangement of the trailing cable of overhead
crane.
Figure 2: is the assembly of the cable trolley which need replacement of wheels.
Figure 3: is the schematic illustration of the tool for maintenance/replacement of
trailing cable carrier trolley according to the present invention for overhead cranes.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS.
Present invention is directed to providing an adjustable lifting tool/tackle for faster and
safe maintenance/wheel replacement of trailing cable carrier trolley with less
manpower favoring less downtime and consequently higher production and
productivity.
Accompanying Figure la and lb shows the general arrangement of the trailing cable
of overhead crane. Accompanying Figure 2 shows the assembly of the cable trolley
which need replacement of wheels. It is already explained that due to the frequent
traveling of the trolley under load of multiple cables laid on cable decker suspended
from the carrier, the rotating wheels of the cable carrier get worn out. These wheels
need to be replaced periodically. The conventional practice of maintenance of cable
carrier and or replacement of wheels thereof is difficult, time consuming and need lot
of manpower.
In order to solve this problem, the present invention provides for an effective lifting
tool, which is having adjustable legs to safely lift the cable carrier for required
maintenance and or replacing the worn out wheel. Accompanying Figure 3 is the
schematic illustration of the tool for maintenance/replacement of trailing cable carrier
trolley according to the present invention for overhead cranes.
The tool for replacement of cable carrier in overhead cranes according to the present
invention is a simple but powerful tool. It has a central C-channel with threaded hook
at two ends for adjusting the leg lengths as per need and chain link with V hook
connected to each of said threaded hook.
The tool consists of a 500mm long C-channel of size 100x50x5mm. Two number holes
are drilled at two ends of the C-channel to fit 10mm dia threaded hook. The length of
the threaded hook is 200mm. Two numbers of 6mm chain assembly is suspended at
both ends from the hooks with suitable arrangement. The length of each chain is
approximately 300 mm. At the other end of the chain one V shape hook is welded. The
hook is made from a MS flat of size 30mmwide x 5mm thick. One end of the threaded
hook is fitted with nut and suitable washer. The length of the threaded hook with chain
can be adjusted by tightening nuts of the above stated threaded hook. The total weight
of the tool is only about 3 kg.
For application of the tool for maintenance of cable carrier, firstly the defective cable
trolley of the crane is to be identified and defective parts of the cable trolley are
marked. New or good spare for the cable trolley is arranged and kept ready on the
crane. The tool for replacing cable carrier is to be kept crosswise on the I-beam just
over the defective trolley. Both the V shape hook is to be kept just below the
semicircular decker(meant for cable support). Both the threaded hooks are then
tightened in such a way that the cable trolley get loose over the I-beam. In this
position the total load of the cable trolley get transmitted to the tool. Now both the
side plates (part no. 35 of Figure 2) can be removed for replacing cable trolley
wheel(part no. 33 of Figure 2). All the defective parts as illustrated in Figure 2, can be
removed for replacement except the cable carrier semicircular decker, because it is
supported by the tool. After replacing all the defective parts, all the nuts and studs are
to be tightened and now the cable carrier is ready for operation. The load on the tool
now can be released by loosening the threaded hook nuts and the tool can be removed
from the position.
The following advantages are derived from the application of the invented tool for
trailing cable carrier maintenance/replacement of spares:
1. With the help of the present tool, parts of the cable trolley can be replaced
within an hour.
2. No special safety precaution is required during maintenance/replacement of
spares.
3. The tool is very easy to operate.
4. It can bear all the load on the cable trolley as there may be many cables
embedded over the trolley.
5. Only one person can change the parts of the cable trolley with the help of this
tool.
6. Production and productivity is significantly improved as the down time of the
crane is reduced drastically.
7. Very less manpower is required to replace a defective cable carrier and only two
persons will suffice.
8. The tool can be operated at any height over the crane, including in converted
design of crane.
9. design and construction of the tool is very simple and can be fabricated in any
small workshop.
10. The total cost of the tool is very less of the order of few hundreds only.
11. No past experience is required to handle and use the tool for the desired
purpose.
It is thus possible by way of the present invention to developing a tool for
maintenance of trailing cable carrier trolley for replacement of worn out wheels in
overhead cranes in less time and with less manpower in faster and safe manner, so
that possibility of accident/injury of personnel is avoided. The tool is easy to
fabricate, light weight and simple to operate so as to maintain/repair or replace
parts of the trailing cable carrier trolley of overhead crane with reduced down time
and improved productivity while cables need not be removed during such
repair/replacement.
We Claim:
1. A system for replacement of spares in trailing cable carrier trolley in overhead
cranes, comprising
a c-channel;
a pair of hook means spaced apart and supported with respect to said C-channel;
said hook means secured with respect to said C-channel such as to enable lifting of the
cable carrier when hooked thereto by means adapted to release and retract the vertical
height of the respective hooks from said C-channel.
2. A system for replacement of spares in trailing cable carrier trolley in overhead
cranes as claimed in claim 1 comprising
said c-channel;
said pair of hooks having threaded and nut fixed at each of said c-channel through
drilled holes facilitating said release and retract the vertical height of the respective
hooks from said C-channel for lifting of cable trolley for replacing parts;
a sling chain of suitable length with a V hook welded at the bottom end is suspended
from each threaded hook for gripping the cable decker below the carrier trolley prior to
lifting.
3. A tool for replacement of spares in trailing cable carrier trolley as claimed in anyone
of claims 1 or 2 wherein said C-channel is of size 100x50x5mmthick and 500mm long.
4. A tool for replacement of spares in trailing cable carrier trolley as claimed in anyone
of claims 1 to 3 wherein said threaded hook with nut is 10 mm in dia and 200 mm
long.
5. A tool for replacement of spares in trailing cable carrier trolley as claimed in anyone
of claims 1 to4 wherein each said sling chain is 6mm chain assembly of 300 mm
length with said V shaped hook welded at bottom end made of chain is made of MS flat
of size 30mmwide x 5mm thick.
6. A method for replacement of spares in trailing cable carrier trolley in overhead
cranes using the tool as claimed in anyone of claims 1 to 5 comprising the steps of:
(i) placing the tool for replacing cable carrier crosswise on the I-beam just over
the defective trolley to be repaired/replaced with spares;
(ii) positioning both the V shape hook of chain link attached to threaded hook
just below the semicircular decker(meant for cable support) with cables laid
therethrough, so as to grip the decker from two sides;
(iii) tightening nuts of both the threaded hooks in such a way that the cable
trolley get loose over the I-beam so that the total load of the cable trolley
get transmitted to the tool;
(iv) loosening and removing the studs, nuts and side plates to remove the
parts/wheel to be replaced;
(v) remove worn out parts/wheel and replacing with new /good spare/wheel ;
(vi) tightening the studs and nuts after placing the side plates after
repair/replacement of spare/wheel;
(vii) releasing the load on the tool by loosening the nuts of the threaded hook
(viii) removing the tool from the position and check for satisfactory operation of
the cable carrier trolley with replaced parts.
7. A tool for replacement of spares in trailing cable carrier trolley in overhead cranes
and a method for replacement of spares of cable carrier using said tool substantially as
hereindescribed and illustrated with reference to the accompanying drawings.

ABSTRACT

The present invention relates to a system for servicing/maintenance of trailing cable
carrier trolley in overhead cranes involving a simple light weight easy to operate
adjustable tool. More particularly, the present invention is directed to providing a
simple and user friendly tool in the form of an adjustable lifting tackle for lifting the
trolley for servicing of trailing cable carrier trolley in overhead cranes or replacement of
wheels/parts thereof in a faster and safe manner using less manpower, without
needing dismantling of cables.