Formula Selection Method
1. Select Coupling Type
Refer to Page 5 and select the type of coupling to suit your application. If an application requires a special purpose coupling, refer application details to the local Folk Representative.
2. Determine Service Factor or System Peak HP
A. For MOTOR, TURBINE or ENGINE driven applications, refer to Tables 1 and 2.
B. For BRAKE and HIGH PEAK LOAD applications, refer to Step 3 below.
3. Calculate Required Rating
The coupling hp per 100 rpm rating or torque rating must equal or exceed the application requirements. Determine the required coupling rating using the formula in Step 3A and the applicable formula from Steps 3B and 3C. Use the highest required rating to determine the coupling size in Step 4.
A. NORMAL SERVICE: HP per 100 RPM = (Transmitted HP x 100 x SF) / RPM
Transmitted hp equals the measured hp or if not available, the motor or turbine rated hp with the exceptions noted below.B. BRAKE APPLICATIONS: Use the brake hp in the above formula if it exceeds the prime mover hp rating.
C. REPETITIVE HIGH PEAK LOAD APPLICATIONS: Use one of the following applicable formulas for applications using motors with torque characteristics that are higher than normal, applications with intermittent operation, shock loading, inertia effects due to starting and stopping and/or system induced repetitive high peak torques. The "System Peak Torque" is the maximum that can exist in the system.
a. For NON REVERSING SERVICE: Req'd Coupling Torque Rating = System Peak Torque
b. For REVERSING SERVICE: Req'd Coupling Torque Rating = 2.0 x System Peak Torque
4. Determine Coupling Size
A. Refer to Table 5 - Trace down the HP per 100 RPM column or the Torque Rating column to a figure equal to or in excess of the highest calculated value in Step 3. Read coupling size at left.
B. Check shaft diameters against coupling maximum bores shown in Tables 9 thru 11 for the type of coupling selected. If a larger bore is required, select a larger coupling.
C. Cheek the required speed against the allowable speed shown in Table 5 for the type of coupling selected. For Type T50 Floating Shaft design, check the allowable speed from Table 8 on Page 17. If a higher speed is required, refer application details to the local Folk Representative.
D. Cheek application dimension requirements against selected coupling type dimensions shown on Pages 10 thru 19.
Example:
Normal Load Method
Select a coupling to connect a 450 hp, 1170 rpm electric motor to the reducer high speed shaft of a manoeuvring winch. Maximum shaft gap is .25" The motor shaft diameter is 3.500" with a keyway of .875" x .438". The reducer high speed shaft diameter is 3.000" with a keyway of .750" x .375". The motor and reducer shaft extensions are each 6.00" long.
1. Select Coupling Type - To connect close coupled shafts (.25" maximum gap), the Type T10 or T20 coupling is the proper selection. Type T20 is selected.
2. Determine Service Factor - From Table 1, the service factor is I.S.
3. Calculate Required Rating - Use the Normal Service Formula from Step 3A.
HP per 100 RPM = (Transmitted HP x 100 x SF) / RPM
HP per 100 RPM = (450 x 100 x 1.5) / 1170 = 58
4. Select Coupling Size - (A) From Table 5, the coupling size 1100T20 with a rating of 80 hp per 100 rpm. (B) From Table the maximum bore with square key is 4.000". (C) From Table the allowable speed is 3250 rpm.(D)Dimensions for the 1100T20 coupling shown on Page 11 satisfy the application requirements
Example:
Peak Load Method
Select a coupling for reversing service to connect a gear reducer low speed shaft to a runout mill table roll. The electric motor rating is 50 hp at the base speed and the system peak torque at the coupling estimated to be 150,000 pound-inches. Coupling speed is 77 rpm x the motor base speed. The reducer shaft diameter is 4.000" with keyway of 1.000" x .500". The runout table roll diameter is 5.25 (with a keyway of 1.250" x .625". Maximum shaft gap is 7.00". The motor and reducer shaft extensions are each 7.00" long.
1. Select Coupling Type - To connect a maximum shaft gap 7.00", the Type T35 is the proper selection.
2. Calculate Required Rating
a. NORMAL SERVICE FORMULA (Step 3A) - From Table 1, the service factor is 3.0
HP per 100 RPM = (Transmitted HP x 100 X SF) / RPM
HP per 100 RPM = (50 x 100 x 3.0) / 77 = 195b. REVERSING SERVICE FORMULA (Step 3Cb)
Req'd Coupling Torque Rating = 2.0 x System Peak Torque or 2.0 x 150,000 lb-in. or 300,000 lb-in.3. Determine Coupling Size - (A) From Table 5, coupling size 1130T with a rating of 254 hp per 100 rpm. For a torque 300,000 pound-inches, select the larger size coupling; 115( (B) The 1 ISOT35 shown on Page 15, has a maximum "BE" dimension of 7.38". The shaft hub has a maximum bore 10.000" with one rectangular key (Table 10). The T hub has maximum bore of 8.000" with one rectangular key (Table 9). (1 From Table 5, the allowable speed for the 1 150T35 is 1500 rpm (D) Dimensions for the 1150T35, shown on Page 15, satisfies the application requirements.
Table 5: Coupling Ratings & Allowable Speeds
Coupling
SizeHP per
100 rpm *Torque Rating
(lb-in.) *Allowable Speeds # - rpm
T10
T20 &
T50 @T31, T35 &
T10/G82T70
1020T
.67 422 4500 6000 3600 --
1030T
1.90 1,200 4500 6000 3600 10000 1040T
3.17 2,000 4500 6000 3600 -- 1050T
5.56 3,500 4500 6000 3600 9000 1060T
8.73 5,500 4350 6000 3600 -- 1070T
12.7 8,000 4125 5500 3600 8200 1080T
26.2 16,500 3600 4750 3600 7100 1090T
47.6 30,000 3600 4000 3600 6000 1100T
80.0 50,500 2440 3250 2440 4900 1110T
119 75,000 2250 3000 2250 4500 1120T
175 110,000 2025 2700 2025 4000 1130T
254 160,000 1800 2400 1800 3600 1140T
365 230,000 1650 2200 1650 3300 1150T
508 320,000 1500 2000 1500 --
1160T
714 450,000 1350 1750 1350 --
1170T
952 600,000 1225 1600 1225 --
1180T
1,320 832,000 1100 1400 1100 --
1190T
1,750 1,100,000 1050 1300 1050 --
1200T
2,385 1,500,000 900 1200 900 --
1210T
3,175 2,000,000 820 --
--
--
1220T
4,290 2,700,000 730 --
--
--
1230T
5,555 3,500,000 680 --
--
--
1240T
7,140 4,500,000 630 --
--
--
1250T
9,520 6,000,000 580 --
--
--
1260T
11,900 7,500,000 540 --
--
--
* HP per 100 rpm and torque rating values for hubs with Taper Lock brushings differ from those shown above; refer to table 13.
# Consult Factory for speeds higher than those shown.
@ Speeds shown above are for single Type T50 couplings; speeds for Type T50 Floating Shaft couplings are shown in Table 8 on Page 17.