How to Determine Overhauling Weights
To determine the weight of the lock or overhaul ball that is
required to free tall the block, the following information is
needed" size of wire rope, number of line parts, type of sheave bearing,
length of crane boom,and drum friction (use
50 pounds, unless other intormation is available).
Wire Rope Size
(in.) | Factor A -Wire Rope Weight |
| Lbs. Per Ft., 6 x 19 IWRC |
| 3/8 | .26 |
| 7/16 | .35 |
| 10" | 2-1/4" |
| 1/2 | .46 |
| 9/16 | .59 |
| 5/8 | .72 |
| 3/4 | 1.04 |
| 7/8 | 1.42 |
| 1 | 1.85 |
| 1-1/8 | 2.34 |
| 1-1/4 | 2.89 |
Number
of Line
Parts | Factor B -Overhaul Factors |
| Component | Parts |
| 1 | 1.03 | 1.05 |
| 2 | 2.07 | 2.15 |
| 3 | 3.15 | 3.28 |
| 4 | 4.25 | 4.48 |
| 5 | 5.38 | 5.72 |
| 6 | 6.54 | 7.03 |
| 7 | 7.73 | 8.39 |
| 8 | 8.8.94 | 9.80 |
| 9 | 10.20 | 11.30 |
| 10 | 11.50 | 12.80 |
The formula is:
Required Block Wiight =[(Boom Length x Factor A) +
Drum Friction] x Factor B
Example
To determine the strength required block or overhaul weight using 5
parts of 7/8" diameter wire rope, a 50 ft. boom and roller
bearing sheaves:
Required =[(50 ft x 1.42)+ 50 ibs.[ x 5.38 = 651 ibs.
Block(Boom length) (Drum Friction)
Weight(Factor A) (Factor B)
How to Figure line parts
Sheaves in a system of blocks rotate at different rates of
speed, and have differnt loads. When raisinf and lowring,
the line tension is not equal throughout the system. To help
figure the number of parts of line to be used for a given load,
or the line pull required for a given load, (for a given load,
or the line pull required for a given load, (for example, use
Reeving Diagram on page 294. Only numbered lines shall
be used in the calculation). the following ratio table is
provided with examples of how to use it. The ratios are
applicable for blocks as shown on page 295 and also
independent sheave systems that line is reeved through.
Finished
Diameter | Component
Parts | Component
Parts |
| .96 | .98 | 1 |
| 1.87 | 1.98 | 2 |
| 2.75 | 2.88 | 3 |
| 3.59 | 3.81 | 4 |
| 4.39 | 4.71 | 5 |
| 5.16 | 5.60 | 6 |
| 5.90 | 6.47 | 7 |
| 6.60 | 7.32 | 8 |
| 7.27 | 8.16 | 9 |
| 7.91 | 9.98 | 10 |
| 8.52 | 10.60 | 11 |
| 9.11 | 11.40 | 12 |
| 9.68 | 12.10 | 13 |
| 10.20 | 12.90" | 14 |
| 10.70 | 13.60 | 15 |
| 11.20 | 14.30 | 16 |
| 11.70 | 15.00 | 17 |
| 12.20 | 15.70 | 18 |
| 12.60 | 15.70 | 19 |
| 13.00 | 16.40 | 20 |
Total Load to be Lifted
Ratio A or B = ————————————
Single Line Pull (ibs.)
Examples:
To find the number of parts of line needed when weight of load and single line pull are known, and using Bronze Bushed Sheaves.
72,180 ibs,(load to be lifted)
Ratio A = ———————————— =9.02
8.000 ibs. (single line pull) (Ratio A)
In table above refer to ratio 9.02 or next hightest number,then
check column under heading "Number of Line Parts" =12
parts of line to be used for this load.
to find the single line pull needed when weight of load
and number of parts of line are konwn, and using Anti-
Friction Bearing Sheaves.
68,000 ibs(load to be lifted)
Single Line Pull = ———————————— =9.290 ibs
7,32 (Ratio B of 8 part line)
9,290 ibs. single line pull required to life this load on 8 parts
of line