FIELD OF INVENTION
The present invention relates to an improved steel transfer car gear boxes
parting line bolts fixing arrangement in a steel plant. More particularly, the
present invention relates to a nut and bolt fixing arrangement for a parting line
joining to arrest the high jerk loads experienced by the steel transfer car.
BACKGROUND OF THE INVENTION
In steel plant, there is a steel transfer car which is used to transport empty and
full steel ladles to and from the converter in Bay area in between column. These
steel transfer car having two gearboxes with half threaded type bolts in parting
line halves.
Presently steel transfer car of LF#3 at LD1 is driven by two drives thus two gear
boxes. Both gear boxes having half threaded type parting line bolts fixing

arrangement. There is high no. of bolts failure from the neck of threaded
portion. For solving this problem a RCFA analysis was carried out.
In this analysis we found that the existing bolt fixing arrangement (Half threaded
in parting line) is not adequate to take loads and needs to be changed with stud
type bolt (through bolt with nut) fixing arrangement.
In steel transfer car application where high jerk loads are there, stud type (NUT
AND BOLT) bolts fixing arrangement for parting line joining is suitable rather
than existing half threaded bolts fixing arrangement which have tendency to
break from the thread neck position.
The modifications improve the service factor and maintainability of the gear
boxes.
OBJECT OF THE INVENTION

Therefore, it is an object of the invention to propose an improved steel transfer
car gear boxes parting line bolts fixing arrangement which is capable of
withstanding high jerk loads during the movement of the steel transfer car.
Another object of the invention is to propose an improved steel transfer car gear
boxes parting line bolts fixing arrangement which can eliminate the possibility of
a failure of the fixing arrangement during the use of the steel transfer car.
SUMMARY OF THE INVENTION
In this invention, the gear box parting line bolts fixing arrangement from screw
type to nut and bolts type arrangement is adapted where the sizes of the bolts
are increased. In which the bottom housing of gear box need not to be threaded
and through hole is required to fit the nut and bolt assembly.
Screw type bolts fixing arrangement could not take high impact loads and having
tendency to break from the threaded neck which is completely overcome by
using nut and bolt type fixing arrangement.

In the prior art 18 nos. of parting line bolts of size M16 and M20 were used to
join gear box and all are having screw type (half threaded) assembly.
With the help of invention and study the bolts fixing arrangement are changed
from screw type to nut and bolt type. Bolt sizes also modified (as found under
design) from M16 to M20 and M20 bolts to M24 bolts.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Shows the gear box parting line screw type arrangement according
to the prior art.
Figure 2 - Shows the Gear box parting line nut and bolt type arrangement,
according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The design of screw type bolts fixing and their load carrying capacity were
checked and found the calculated pitch of bolts is coming 120 mm while actual is

400mm. This indicates that the bolts of M20 size are subjected to more load as
compared with standard design of GB which is inadequate.
As well as with respect to bolts size their factor of safety is coming only 1.1
which is very less for the steel transfer car application where high heat and harsh
working conditions are present.
Both design parameters clearly indicates that the existing bolts sizes are
inadequate for this application and needs to be changed.
The bolts fixing arrangement (screw type) having half threaded portion which is
to be fixed in bottom housing of GB. If there is a high impact load (which is a
normal condition for steel transfer car application) bolts having tendency to
break from the neck of thread portion, which is not a good design for such
application. A complete nut and bolt system rather than threaded assembly will
take high axial, radial and bending loads.
From this basis the bolt fixing arrangement is changed to nut and bolt type.

WE CLAIM
1. A steel transfer car gear boxes parting line bolts fixing arrangement
comprising;
a plurality of bolts passing through the holes made on the base of the
gear boxes for parting line joining characterized in that,
a plurality of nuts engage the bolts coming out of the through holes fixing
the bolt tightly.
2. A fixing arrangement as claimed in claim 1, wherein M20 and M24 bolts
are provided in the fixing arrangement for making the assembly rigid for
taking high axial, radial and bending loads.