Wichita Clutch LK Brake - Manual (Page 4)

B
Air Tube Disc Clutches and Brakes
P-1100-WC 1/12 Wichita Clutch 800-964-3262 25
Summary
As calculated, the torque required to stop the
load in 5 seconds is 14,547 lb.in. Wichita Low
Inertia Brakes are rated at 100 PSI.
This application has only 80 PSI available.
To determine the torque rating of a Low Inertia
brake at 80 PSI apply the following formula:
Application: Torque for a Low Inertia Brake
=
Torque X Catalog Rated Pressure
Available Air Pressure
= 14,547 X = 18,183 lb.in.
Consult pages 26 and 36 for clutch and brake
spec i fi ca tions. A Low Inertia model 114 Brake
pro duc es 27,625 lb.in. torque at 100 PSI.
However, the bore capacity is 4.125 inches.
This application requires a 5 inch bore.
There fore, a Low Inertia 118 is to be
in ves ti gat ed.
Catalog Torque Rating = 64,500 lb.in.
@ 100 PSI
Maximum Bore Capacity = 5.25 in.
Catalog Swept Friction Area = 264 in.
2
Calculations show this application needs at
least 202 in.
2 to absorb the heat.
All of these ratings are acceptable for the given
application data.
Next, check contact velocity of rotating discs.
=
Diameter of centerplate X RPM
3.82
=
18" X 750
3.82
= 3,534 FPM
Standard material is sufficient up to 6,000 FPM
(see page 23). Balancing is recommended
above 3,500 FPM.
Therefore, a Low Inertia ATD-118 brake is
the optimum choice for this application.
A Spring-Set Air Release Brake is also
available (see page 58).
Note:
This application example is for pre lim i nary
sizing only. Contact a Wichita Sales Engineer
or the factory for final selection.
Selection Requirements
The selection of a Low Inertia Brake is
based on:
1. Torque required to stop a load.
2. Friction area necessary to absorb
rotational energy.
3. Contact velocity of rotating discs.
4. Maximum bore capacity of unit.
Selection example
To properly select a Low Inertia Brake for
a controlled deceleration application, the
following information is needed:
Speed . . . . . . . . . . . . . . . . . . 750 RPM
Shaft Dia.. . . . . . . . . . . . . . . . 5 in.
Inertia to Stop . . . . . . . . . . . . 2,473 lb.ft.
2
Stop Time . . . . . . . . . . . . . . . 5 sec.
Air Pressure Available . . . . . . 80 PSI
Calculations
Avg. HP =
WR 2 X (RPM) 2
3.2 x 10 6 x Stop Time
=
2,473 X (750) 2
3.2 x 10 6 x 5 sec.
= 87 HP
Swept Avg. HP
Friction
=
HP ab sorp tion rate for 5 seconds
Area (see page 174)
= 87 HP = 202 in.
2
0.43
Torque =
WR 2 x RPM
25.5 x Stop Time
=
2.473 x 750
25.5 x 5
= 14,547 lb.in.
Using the above calculations, consult the
Low Inertia Specifications Chart on
pages 26 and 27.
100
80
Low Inertia and Very Low Inertia Clutches and Brakes