Flexible gear coupling inspection port

An inspection port to permit inspection of internal gears in a flexible coupling of the type used to connect rotating shafts in machinery.

BACKGROUND OF THE INVENTION 
This invention relates to flexible gear couplings used to connect rotating 
shafts in machinery. It relates particularly to a means of inspecting the 
gears used in such couplings. 
Flexible couplings are commonly used for connecting rotary shafts in 
machinery such as the shafts connecting an electric motor to a pump. Such 
couplings are very useful in prolonging the life of the machinery since 
the repeated flexing of rigidly coupled rotary shafts, regardless of how 
slightly they are misaligned, can produce severe stresses in the shafts, 
the bearings and the machinery. Also excessive stresses can be incurred 
when the normal axial movement of rigidly coupled rotary shafts is 
constrained. A flexible coupling on the shafts permits such excessive 
stresses by compensating for any misalignment of the shafts or axial shaft 
movement, while at the same time transmitting the torque from one shaft to 
the other. 
Gear type flexible couplings are manufactured by many manufacturers of 
mechanical power transmission equipment and are widely used in industry. 
The gear-type coupling consists of two similar hubs with external gear 
teeth and a floating sleeve assembly with internal gear teeth. The hubs 
are fitted to the ends of the driving and driven shafts, and as the 
driving shaft rotates, the driving hub gear teeth engage the internal gear 
teeth of the floating sleeve assembly so that the entire coupling rotates 
as a unit. 
Flexible gear couplings, like any other piece of rotating machinery, are 
subject to excessive wear if not properly lubricated and maintained. In 
addition, flexible gear couplings are frequently subjected to starting and 
stopping impact loads that can damage the gears, if excessive. As a result 
flexible gear couplings need to be regularly inspected and repaired or 
replaced if necessary. Regular inspections are often required by OSHA 
regulations. The sealed sleeve over the hubs prevents a visual inspection 
of the conditions of the gears on the hubs and the gears in the sleeve. An 
inspection requires the removal of the motor or prime mover and a complete 
disassembly of the flexible gear coupling, which is time-consuming and 
expensive. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a means for quickly and easily 
inspecting the condition of the gears in a flexible gear coupling. 
It is a further object of this invention to provide a means for inspecting 
the condition of the gears in a flexible gear coupling that can be easily 
applied to all types of gear couplings and to couplings now in service. 
It is a further object of this invention to provide a flexible gear 
coupling that will provide longer trouble-free service. 
It has been discovered that the foregoing objectives can be attained by a 
flexible gear coupling having an inspection aperture in the sleeve 
assembly which extends through the sleeve assembly and through the central 
section of at least one tooth of the internal gear teeth of the sleeve 
assembly of the coupling.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
FIG. 1 illustrates a flexible gear coupling of the type for which this 
invention is useful. 
As shown in FIG. 1, flexible gear coupling 1 comprises a pair of hubs 2 and 
2' and a pair of sleeve members 6 and 6' which are bolted together to form 
a sleeve assembly 5. The hubs 2 and 2' each have a keyway 3 to secure a 
cylindrical shaft (not shown). A ring of gear teeth 4 is formed on the 
external surface of each of hubs 2 and 2'. The hubs 2 and 2' are usually 
of the same diameter. 
Surrounding the hubs 2 and 2' is a sleeve assembly 5 consisting of mating 
flanged sleeve members 6 and 6' which are connected together at their 
flanges 7 and 7' by bolts 8. The sleeve members 6 and 6' are each provided 
with an internal ring of gear teeth 9 positioned to engage the external 
gear teeth 4 of hubs 2 and 2' when the coupling 1 is assembled. 
As the driving shaft (not shown) rotates hub 2, the external gear teeth 4 
of hub 2 engage the internal gear teeth 9 of the sleeve member 6 causing 
the entire sleeve assembly 5 to rotate and in turn rotate hub 2' and the 
driven shaft (not shown) connected thereto. 
The sleeve members 6 and 6' are provided at their outer ends with O-rings 
10 or similar seals which engage the hubs 2 and 2' to prevent dirt and 
water from entering the coupling 1 and to retain a lubricant within the 
coupling 1. Some couplings have a mechanical configuration designed in the 
sleeve end that maintains the required lubricant level without the need 
for a resilient seal. Most couplings of this type require an internal 
lubricant which injected into the coupling 1 through a lubrication passage 
11 formed in the flanges 7 and 7' of the sleeve members 6 and 6'. 
In accordance with this invention, each sleeve member 6 and 6' is provided 
with an inspection port or aperture 15 extending through the sleeve 6 and 
6' and through the central section of at least one tooth 16 of the 
internal gear teeth 9 of the sleeve members 6 and 6'. Since the hubs and 
sleeves never disengage, the wear seen on one tooth is indicative of the 
wear on all the teeth. 
As best shown in FIG. 2, which is an enlarged view of what one would see in 
looking through the inspection aperture 15 of this invention, the central 
section of at least one tooth 16 is removed leaving the side sections 17 
and 17' of that tooth in place. The removal of the central section of 
tooth 16 exposes the profile of the side sections 17 and 17' and the tooth 
thickness and also the face flanks of teeth 4 on the hubs 2 and 2' to a 
visual inspection through the inspection aperture 15. Preferably, the 
aperture 15 is in a circular hole whose center is aligned with the 
midpoint of the width of the internal gear teeth 9 of the sleeve members 6 
and 6'. The diameter of the aperture 15 should be greater than two times 
but less than three times the pitch of the external gear teeth 4 on the 
hubs 2 and 2' to permit an inspection of two hub teeth thickness 
conditions at a time. The bottom of the aperture 15 is formed by the tops 
of gear teeth 9 adjacent to gear tooth 16. 
FIG. 3 is a sectional view of the inspection aperture showing the means to 
seal said aperture 15 between inspections. The seal is a resilient 
elastomer plug 20 having a head 21 and shank 22 and a circumferential 
shoulder 23 between the head 21 and the leading end 24 of the shank. When 
inserted in aperture 15, the shoulder 23 of plug 20 fits into a 
circumferential groove 25 in the sleeve assembly around the aperture 15 to 
retain the plug 20 in place. 
The exact dimensions of the aperture 15 and plug 20 will vary according to 
the size of the coupling 1. The inspection aperture 15 can be easily 
machined in the sleeve members 6 and 6' of all flexible gear couplings on 
the market although the exact location and size may vary according to the 
specific brand of coupling used. 
While the present invention has been described and illustrated with our 
preferred embodiment, it will be appreciated by those skilled in this art, 
after understanding this invention, that various changes and modifications 
may be made without departing from the spirit and scope of this invention. 
It is therefore intended that all such changes and modifications will be 
included in the following claims.