Tork-trol
Shear-Pin Hubs, Your Best Choice For Complete Protection: Here's Why . . .
• All-Steel Construction
Tork-Trol hubs are compact and strong . They take less space on the shaft and have higher torque ratings than cast iron or iron-on-steel hubs of similar size.
• Corrosion-Resistant Bronze Bushings
Hub sections that rotate when a pin shears are separated by a bronze bushing. They can't fret or corrode together . Breakaway torque is always uniform and repeatable .
• Disc-Type Design
Pins are located in a solid steel disc , which is much stronger and more reliable than
"arm-type " designs . Disc-type design also makes it possible to provide multiple pin locations where desired.
• Pins Mounted In
Special Shear Bushings
Heat treated , sharp-edged shear bushings are press-fit at the head to provide a true shearing action . Pin bending, common with ordinary drill bushing equipped hubs, is minimized for more reliable operation .
• Welded Steel Sprockets
Standard construction on Tork-Trol hubs, eliminates the inherent problems of bolted sprockets . Hub and sprocket are welded together for maximum strength .
• Outstanding Versatility
Two standard styles , and the widest range of stock sizes in the industry make Tork-Trol hubs your best choice for most applications . And , where a special hub is needed, Tork-Trol 's simple design makes modification quick and inexpensive .
Tork-Trols are premium quality shear-pin hubs, designed to protect heavily loaded, slow-speed drives against damage from overloads and stalls. They are built in two styles with standard bore sizes from 7/8" to 9112'' . Larger bores available on request.
Use them with Murray's precision flame-cut steel conveyor sprockets, compensating drive sprockets , or roller chain sprockets , to build reliable , low-cost, shear-pin protected drives for your equipment. They combine the advantages of custom-built drives with the economy of standard , off-the-shelf components and the strength of all-steel construction .
Selection Procedure
Hub & Sprocket Size
Hub size and the minimum number of teeth on the sprocket it carries are both related to shaft diameter . Refer to Table 2 to select the proper Tork-Trol hub to fit your shaft size , and then read the minimum number of teeth required on your roller chain sprocket , for that hub. If your sprocket has the minimum number of teeth or more, procede with the torque and pin neck diameter calculations below .
If your application involves a sprocket with fewer teeth than the minimum indicated in Table 2, Murray can probably provide a special Tork-Trol hub designed to accommodate it.
Other hub modifications are also possible to meet special needs. Consult your distributor or Murray's engineering department for assistance.
Torque Load
& Pin Neck Diameter
Use one of the three methods listed below to determine the torque load on the hub. Once the load is known, consult Table 3 and select an appropriate shear -pin neck diameter to carry it.
Symbols
T - Torque in inch pounds
HP - Horsepower at the sprocket RPM - Sprocket revolutions per minute
R - Sprocket pitch radius CP - Chain pullin pounds 1.5 - Starting load factor
Method A
When reducer output torque and drive speed ratio are known.
T= Output torque X
Drive Speed Ratio X 1.5
Method B
When horsepower at sprocket and sprocket RPM are known.
T= HP X 63000 X 1.5
RPM
Method C
When chain pull and sprocket pitch radius are known.
T= CP X R X 1.5
Selection Example
Select a Tork-Trol assembly for a conveyor chain drive:
Conveyor Requirements: Head shaft requires 5 HP at 22.8 RPM, with 1925 lbs. chain pull.
Conveyor sprocket pitch diameter is 14.334 in. and head shaft diameter is 2-7/16 in.
Drive Specifications: Motor; Reducer with 4600 in. lbs. torque output ; and 3:1 ratio chain drive consisting of RC80, 15-tooth and RC80
45-tooth sprockets. (Pitch diameter of RC80A45 sprocket is 14.334 in.).
Hub & Sprocket Size
Refer to Table 2: A #25-2 Tork-Trol hub will fit the 2-7/16 in. diameter head shaft. The
RC80A45 sprocket will fit the 25-2 hub and has more than the minimum number (28) of teeth .
Find Torque Load
& Pin Neck Diameter:
Method A
Known: Speed reducer output torque (4600 in. lbs.)
Speed ratio of chain drive (3:1)
|
T = 4600 x 45 x 1.5 = 20,700 in. lbs.
15
Method B
Known: Head shaft HP (5)
Sprocket RPM (22.8)
T = 5 x 63000 x 1.5 = 20,700 in. lbs
22.8
Method C
Known: Chain pull (1925 lbs.)
Sprocket pitch radius (7.17)
T = 1925 x 7.17 x 1.5 = 20,700 in. lbs.
After determining the torque load, refer to Table 3 to select the appropriate pin neck diameter.
It shows 3/8-in. diameter pin neck will shear at 20,700 in. lbs.
To Order:
The part number for the appropriate Tork-Trol hub will be: 80A45 x 2-7/16 bore Tork-Trol Shear-Pin Hub Sprocket with a #25-2, Type A hub, Pin neck 3/8-in.
