Girth Gears
Designing Girth Gears
For designing Girth Gears and pinions, there are today several standards.
The most common and popular standards are AGMA 321.05, AGMA 6004 F88 and ISO
6336. The two thing that forms the test of the Gear design are surface
durability(pitting) and tooth bending strength. Both are tested by Hertzian
fatigue stress and the Bending fatigue stress respectively. The image shows
a very large Girth Gear that has a diameter of 8.8 meter used in a steel
industry.
Buyer's consideration for Girth Gears
If you are opting for Girth gears for your production, the following points
can prove to be very useful.
- Proper checking
While zeroing on a girth gear supplier, it is vital to ensure that they
have the requisite facilities for properly performing necessary checks.
This can be the quality attributes like pitch (tooth spacing), profile,
lead angle and other attributes. This would ensure the gear set
functions in a proper fashion.
- Same Supplier
It is imperative to have same suppliers for the pinion as well as the
girth gear. This way it is assured that the pinion and the girth gear
would mate properly at installation without any hitch. Not taking notice
of this can result in unacceptable schedule delay.
- Availability of proper facilities
It is critical to ensure that the supplier of the girth gear has the
capacity for turning the diameters, precisely machine the splits and
easily locate the alignment dowels.
- Cost analysis
A complete cost analysis needs to be performed with attention to
equipment and operating as well as maintenance costs.
- Structure Design
The criteria for structure design of a gear along with material quality
also needs to be considered thoroughly.
Path breaking Advancements in Girth
Gear Materials
Recently there has been remarkable advancements made in the Girth Gear
Material.
- By using state-of-the-art full ring risering technology, castings
are greatly enhanced
- Newer researches in material development is allowing designers to
take advantage of more hardness and, therefore, increased ratings.
- Simulation programs are now used to verify proper solidification
has taken place or not. Numerous examples are run for confirming
that proper sizing of wedges, gates, and risers has been done. This
has a remarkable effect on the casting quality, reduction in the
foundry costs, and total elimination of casting failures.
- Another feature has been added to the cap of the girth gear
technology with the introduction of finite element analysis. With
this technology, it is now possible to calculate not only the
stresses in the structure of girth gear but the gear's deflection
can also be analyzed. Accordingly modifications needed in the pinion
tooth can then be ascertained.
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Other purchase Considerations
Besides the above general instructions some of the very important
considerations with respect to the Gear and pinion of the Girth Gears are
given in the following table.
Maintenance of Girth Gears
The specific methods of maintenance of these gears are as follows:
- Stroboscopic viewing
This is done during the operation of these Gears is operating. It gives
the operator a clear picture of the actual condition of the gear.
- Infrared temperature measurements
Infrared temperature measurements are also done during the these gears
operation. It monitors the load distribution. It gives the operator a
method to schedule and plan the specifics of any alignment, which may be
necessary due to foundation shifts for example.
- Visual examination
Visual examination is done of the teeth during the non operation hours
for example during linear replacement.
- Proper Lubrication
These gears need very sophisticated lubrication systems. Though we
would never even think of running our car engines without lubricant, yet
we are prone to doing so with Girth Gears. The following image shows the
pitfalls of an improper lubrication.
