20 inch

Double-Sheave-J-Block

Key to two sheave J-Block Model Numbers

J 5 D 10 B T A
Shorty “J” Crane Block Safe Working Limit-Tons

Number of Sheaves

Double

Sheave Size – Nom. O.D.

Sheave Bearing:

B = Bronze Bushed
R= Roller Bearing

Hook-Thrust Bearing

Cheek Weights:
A = No wts.
AB = Med. wts.
B = Std. wts.
C = X-Heavy wts.


Model WT. A B E F H J K
Overall Net Thick- Width Throat-Opening Hook Hook
Length
Length
ness
w/Latch
Thick.
Width
J-25D20BTA 520 44.625 40.875 7.750 24.750 3.28 3.00 2.38
J-25D20BTB 820 44.625 40.875 11.437 24.750 3.28 3.00 2.38
J-25D20BTC 1164 44.625 40.875 16.437 24.750 3.28 3.00 2.38
J-25D20RTA 520 44.625 40.875 7.750 24.750 3.28 3.00 2.38
J-25D20RTB 820 44.625 40.875 11.437 24.750 3.28 3.00 2.38
J-25D20RTC 1164 44.625 40.875 16.437 24.750 3.28 3.00 2.38
J-30D20BTA 534 45.125 41.375 7.750 24.750 3.28 3.50 3.00
J-30D20BTB 834 45.125 41.375 11.437 24.750 3.28 3.50 3.00
J-30D20BTC 1178 45.125 41.375 16.437 24.750 3.28 3.50 3.00
J-30D20RTA 534 45.125 41.375 7.750 24.750 3.28 3.50 3.00
J-30D20RTB 834 45.125 41.375 11.437 24.750 3.28 3.50 3.00
J-30D20RTC 1178 45.125 41.375 16.437 24.750 3.28 3.50 3.00
J-35D20BTA 590 48.875 44.625 7.750 24.750 3.27 4.25 3.38
J-35D20BTB 890 48.875 44.625 11.437 24.750 3.27 4.25 3.38
J-35D20BTC 1234 48.875 44.625 16.437 24.750 3.27 4.25 3.38
J-35D20RTA 590 48.875 44.625 7.750 24.750 3.27 4.25 3.38
J-35D20RTB 890 48.875 44.625 11.437 24.750 3.27 4.25 3.38
J-35D20RTC 1234 48.875 44.625 16.437 24.750 3.27 4.25 3.38
J-40D20BTA 748 51.125 46.875 8.625 24.750 3.27 4.25 3.38
J-40D20BTB 1047 51.125 46.875 12.312 24.750 3.27 4.25 3.38
J-40D20BTC 1391 51.125 46.875 17.312 24.750 3.27 4.25 3.38
J-40D20RTA 748 51.125 46.875 8.625 24.750 3.27 4.25 3.38
J-40D20RTB 1047 51.125 46.875 12.312 24.750 3.27 4.25 3.38
J-40D20RTC 1391 51.125 46.875 17.312 24.750 3.27 4.25 3.38
J-45D20BTA 748 51.125 46.875 8.625 24.750 3.27 4.25 3.38
J-45D20BTB 1047 51.125 46.875 12.312 24.750 3.27 4.25 3.38
J-45D20BTC 1391 51.125 46.875 17.312 24.750 3.27 4.25 3.38
J-45D20RTA 748 51.125 46.875 8.625 24.750 3.27 4.25 3.38
J-45D20RTB 1047 51.125 46.875 12.312 24.750 3.27 4.25 3.38
J-45D20RTC 1391 51.125 46.875 17.312 24.750 3.27 4.25 3.38
J-55D20BTA 824 55.500 49.375 8.625 24.750 4.63 6.13 4.00
J-55D20BTB 1123 55.500 49.375 12.312 24.750 4.63 6.13 4.00
J-55D20BTC 1467 55.500 49.375 17.312 24.750 4.63 6.13 4.00
J-55D20RTA 824 55.500 49.375 8.625 24.750 4.63 6.13 4.00
J-55D20RTB 1123 55.500 49.375 12.312 24.750 4.63 6.13 4.00
J-55D20RTC 1467 55.500 49.375 17.312 24.750 4.63 6.13 4.00


Dead End Chart

Wire Rope Size T U For Pin Size
7/16″ thru 5/8″ 1 1.28 1-1/4
3/4″ thru 1″ 1.25 1.65 1-5/8
1-1/8″ thru 1-3/8″ 1.75 2.51 2-1/2

*Gunnebo Johnson Design Factor is 4 to 1, with some exceptions;

45 Ton models 3.6 to 1

60 Ton models 3.7 to 1

325 Ton models 3.7 to 1