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20 inch

Four-Sheave-J-Block

Key to four sheave J-Block Model Numbers

J 15 Q 10 B T A
Shorty “J” Crane Block Safe Working Limit-Tons

Number of Sheaves

Q=4
Quadruple

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
J55Q20BTA 1087 55.750 49.625 14.875 24.750 4.63 6.13 4.00
J55Q20BTB 1387 55.750 49.625 17.750 24.750 4.63 6.13 4.00
J55Q20BTC 1731 55.750 49.625 22.750 24.750 4.63 6.13 4.00
J55Q20RTA 1087 55.750 49.625 14.875 24.750 4.63 6.13 4.00
J55Q20RTB 1387 55.750 49.625 17.750 24.750 4.63 6.13 4.00
J55Q20RTC 1731 55.750 49.625 22.750 24.750 4.63 6.13 4.00
J60Q20BTA 1087 55.750 49.625 14.875 24.750 4.63 6.13 4.00
J60Q20BTB 1387 55.750 49.625 17.750 24.750 4.63 6.13 4.00
J60Q20BTC 1731 55.750 49.625 22.750 24.750 4.63 6.13 4.00
J60Q20RTA 1087 55.750 49.625 14.875 24.750 4.63 6.13 4.00
J60Q20RTB 1387 55.750 49.625 17.750 24.750 4.63 6.13 4.00
J60Q20RTC 1731 55.750 49.625 22.750 24.750 4.63 6.13 4.00
J65Q20BTA 1135 56 49.750 14.875 24.750 4.36 6.25 4.50
J65Q20BTB 1435 56 49.750 17.750 24.750 4.36 6.25 4.50
J65Q20BTC 1779 56 49.750 22.750 24.750 4.36 6.25 4.50
J65Q20RTA 1135 56 49.750 14.875 24.750 4.36 6.25 4.50
J65Q20RTB 1435 56 49.750 17.750 24.750 4.36 6.25 4.50
J65Q20RTC 1779 56 49.750 22.750 24.750 4.36 6.25 4.50
J70Q20BTA 1135 56 49.750 14.875 24.750 4.36 6.25 4.50
J70Q20BTB 1435 56 49.750 17.750 24.750 4.36 6.25 4.50
J70Q20BTC 1779 56 49.750 22.750 24.750 4.36 6.25 4.50
J70Q20RTA 1135 56 49.750 14.875 24.750 4.36 6.25 4.50
J70Q20RTB 1435 56 49.750 17.750 24.750 4.36 6.25 4.50
J70Q20RTC 1779 56 49.750 22.750 24.750 4.36 6.25 4.50
J75Q20BTA 1254 60 53 15 24.750 4.75 6.75 4.75
J75Q20BTB 1555 60 53 17.750 24.750 4.75 6.75 4.75
J75Q20BTC 1899 60 53 22.750 24.750 4.75 6.75 4.75
J75Q20RTA 1254 60 53 15 24.750 4.75 6.75 4.75
J75Q20RTB 1555 60 53 17.750 24.750 4.75 6.75 4.75
J75Q20RTC 1899 60 53 22.750 24.750 4.75 6.75 4.75
J80Q20BTA 1254 60 53 15 24.750 4.75 6.75 4.75
J80Q20BTB 1555 60 53 17.750 24.750 4.75 6.75 4.75
J80Q20BTC 1899 60 53 22.750 24.750 4.75 6.75 4.75
J80Q20RTA 1254 60 53 15 24.750 4.75 6.75 4.75
J80Q20RTB 1555 60 53 17.750 24.750 4.75 6.75 4.75
J80Q20RTC 1899 60 53 22.750 24.750 4.75 6.75 4.75
J90Q20BTA 1502 61.125 53.500 15.500 24.750 4.77 7.63 5.50
J90Q20BTB 1804 61.125 53.500 18.250 24.750 4.77 7.63 5.50
J90Q20BTC 2148 61.125 53.500 23.250 24.750 4.77 7.63 5.50
J90Q20RTA 1502 61.125 53.500 15.500 24.750 4.77 7.63 5.50
J90Q20RTB 1804 61.125 53.500 18.250 24.750 4.77 7.63 5.50
J90Q20RTC 2148 61.125 53.500 23.250 24.750 4.77 7.63 5.50
J100Q20BTA 1502 61.125 53.500 15.500 24.750 4.77 7.63 5.50
J100Q20BTB 1804 61.125 53.500 18.250 24.750 4.77 7.63 5.50
J100Q20BTC 2148 61.125 53.500 23.250 24.750 4.77 7.63 5.50
J100Q20RTA 1502 61.125 53.500 15.500 24.750 4.77 7.63 5.50
J100Q20RTB 1804 61.125 53.500 18.250 24.750 4.77 7.63 5.50
J100Q20RTC 2148 61.125 53.500 23.250 24.750 4.77 7.63 5.50


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