Wichita Clutch Mechanical Power Take-Offs - Manual (Page 6)

Power Take-Off Clutches
150 Wichita Clutch 800-964-3262 P-1100-WC 1/12
Selection Example:
To properly select a Power Take Off (PTO), the following
information is needed:
1. Power transmission type: Inline or Side Load
2. Application engine horsepower @ speed
3. Peak engine torque
4. SAE bell housing size
5. New engine installation or retrofit to an existing engine
6. Duty selection: See chart “A”, page 123
Chart “A” gives application requirements ranging from “Light” to
“Normal” duties (A to B) and “Heavy” to “Extra Heavy” duties (C to
D)
7. Inertia of machine/load
8. Pitch diameters of drive and driven sheaves****
9. Width of drive sheave on Power Take Off shaft****
**** Not applicable to inline drives
Machine Requirement:
Machine Required: Mud Pump – Triplex piston type
Installation: New engine installation
Power
Transmission Type:
Side load
HP & Speed: 300 HP @ 1,800 RPM
Engine Peak Torque: 1,120 lb.ft.
SAE Bell Housing Size: SAE bell housing 1
PD* Driver
Sheave on PTO:
12.5 in.
PD* Driven
Sheave on Mud Pump:
15.0 in.
Width of Driver
Sheave on PTO:
9-3/8 in. (8 grooves –
8V section Belt Sheave**)
WR 2 – Inertia of Pump: 108 lb.ft. 2
* PD is Pitch Diameter of sheave/pulley.
** See manufacturer for sheave details.
Calculations:
1. Application Torque = HP x 63,000/RPM = lb.in.
300 x 63,000/1,800 = 10,500 lb.in.
2. Engine Peak Torque = lb. ft. x 12 = lb.in.
1,120 x 12 =13,440 lb.in.
3. Mud Pump’s Speed =
Engine Speed x P.D. of PTO’s sheave
= RPM
P.D. of Mud Pump’s sheave
1,800 x 12.5/15 = 1,500 RPM
4. Reflect Pump’s inertia up to PTO’s shaft =
Pump’s Inertia x
Pump’s speed 2
= lb.ft. 2
PTO’s speed
108 x
1,500 2
= 75 lb.ft. 2 @ 1,800 RPM
1,800
5. PTO’s clutch slip time, (sec.) =
WR 2 x PTO’s speed
25.6 x Application Torque
=
75 x 1,800
= 1/2 sec.
25.6 x 10,500
6. Estimate Side Load, (lbs.) =
HP x 378,000
Engines Speed x PTO’s sheave PD
300 x 378,000
= 5,040 lbs.
1,800 x 12-1/2
How to Select:
Part 1. PTO Clutch Calculation Follows:
1. Select clutch duty from field of application =
Reference chart “A”, page 123, Petroleum production shows
Mud Pump under duty “D”
2. Determine required HP/100 RPM duty capacity =
Application torque/630 = HP/100 RPM
10,500/630 = 16-2/3 HP/100 RPM
3. Select clutches based on duty =
On clutch capacity chart, page 149,
shows the following clutches have sufficient capacity.
14" Pot, 15-1/2" Flat & 15-1/2" Flat HC
a.) This is a new engine installation and Note 3 states that there may
be an availability problem with the 14" Pot style clutch.
b.) There is not an advantage in capacity to warrant the use of the
15-1/2" Flat HC style clutch. Therefore, preliminary selection of the
clutch is the 15-1/2" Flat style clutch.
4. Peak torque verses clutch torque =
On “C” and “D” duty applications, it is required that the clutch torque
is greater than engine’s peak torque.
15-1/2" Flat clutch torque from clutch specifications chart on page
149 is 19,800 lb. in.
Engine’s peak torque is 13,440 lb.in.
Clutch torque > Engine’s peak torque
19,800 lb.in. > 13,440 lb.in.
5. Speed =
Clutch capacity chart shows that it has a speed limit of 2,100 RPM
which is greater than the required speed of 1,800 RPM.
6. Clutch slip time, (sec.) =
Clutch capacity chart shows maximum clutch slip time as 3 sec.
which is greater than the calculated 1/2 seconds.
Part 2. Side Load Calculation Follows:
Center of sheave’s side pull =
Sheave width/2 = (9-3/8)/2 = 4-11/16 in.
Locate dimension from Bell housing to shaft’s end = 20-15/16 in.
Reference specific PTO drawing
15-1/2" Flat PTO side load, page 148.
Determine “X” distance on PTO =
(Bell hsg. to shaft’s end dim.) - (Center of sheave’s side pull)
(20-15/16) - (4-11/16") = 16-1/4 in.
Round “X” distance to the nearest whole number = 16 in.
Look up side load =
Check side load at PTO’s speed and “X” distance
Page 148, allowable side load.
At “X” distance of 16 in. and 1,800 RPM, chart yields a side load
capacity of 5,800 lbs.
Comparison on side load =
Side load capacity > Required side load
5,800 lbs. > 5,040 lbs.
Final Selection:
15-1/2 in. Flat power take off,
Side load version with SAE "1" Bell Housing
Power take off chart, page 149, lists the associated parts lists and
drawings.
Parts Lists Number = 6-715-299-208-0
Drawing Number = 6-715-202-912-9
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