12 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
J-20Q12BTA 320 29.750 26.750 11.125 16 2.80 3.00 2.38
J-20Q12BTB 440 29.750 26.750 14.750 16 2.80 3.00 2.38
J-20Q12BTC 595 29.750 26.750 19.250 16 2.80 3.00 2.38
J-20Q12RTA 320 29.750 26.750 11.125 16 2.80 3.00 2.38
J-20Q12RTB 440 29.750 26.750 14.750 16 2.80 3.00 2.38
J-20Q12RTC 595 29.750 26.750 19.250 16 2.80 3.00 2.38
J-25Q12BTA 320 29.750 26.750 11.125 16 2.80 3.00 2.38
J-25Q12BTB 440 29.750 26.750 14.750 16 2.80 3.00 2.38
J-25Q12BTC 595 29.750 26.750 19.250 16 2.80 3.00 2.38
J-25Q12RTA 320 29.750 26.750 11.125 16 2.80 3.00 2.38
J-25Q12RTB 440 29.750 26.750 14.750 16 2.80 3.00 2.38
J-25Q12RTC 595 29.750 26.750 19.250 16 2.80 3.00 2.38
J-30Q12BTA 355 33.250 29.500 11.250 16 3.28 3.50 3.00
J-30Q12BTB 475 33.250 29.500 14.750 16 3.28 3.50 3.00
J-30Q12BTC 630 33.250 29.500 19.250 16 3.28 3.50 3.00
J-30Q12RTA 355 33.250 29.500 11.250 16 3.28 3.50

3.00

J-30Q12RTB 475 33.250 29.500 14.750 16 3.28 3.50 3.00
J-30Q12RTC 630 33.250 29.500 19.250 16 3.28 3.50

3.00

J-35Q12BTA 419 39 34.750 11.250 16 3.27 4.25 3.38
J-35Q12BTB 540 39 34.750 14.750 16 3.27 4.25 3.38
J-35Q12BTC 692 39 34.750 19.250 16 3.27 4.25 3.38
J-35Q12RTA 419 39 34.750 11.250 16 3.27 4.25 3.38
J-35Q12RTB 540 39 34.750 14.750 16 3.27 4.25 3.38
J-35Q12RTC 692 39 34.750 19.250 16 3.27 4.25 3.38


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