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Crane Grab Introduction

DATE: Jun 10th, 2023
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Grab, crane grab exactly, is to grab loose bulk material.
Kingda cane grab is organized by two jaws or many jaws assembly together to form a material saving space. During material loading process, the grab is opened and fallen down on material stacks; open-close rope is tension and the grab is closed, at the same time, the supporting rope is pull up, lifting grab to suitable height and transporting to pointed position by upper crane; Thus, release open-close rope, materials are unloaded in wanted areas.


Kingda crane grab, integrated with overhead crane or gantry crane, no need heavy labor, can achieve high loading-unloading efficiency and safety factor, mainly used in ports, power station, steel production plant, yard, chemical factory, scrap yard, ports, mines and railways, water recycling and so on.

Different application environment, using different type grab, this this article, we mainly talking about the following crane grab.

          

1. Four rope crane Grab

Four rope crane grab ( four rope mechanical grab) is used under the integration of gantry crane or overhead crane for grabbing all kinds of loose bulk material, loading, unloading, transportation and material feeding operation.
Different crane grab size to grab different material (density), we usually divide grab working level into light duty, medium duty, heavy duty and super heavy duty, all depending on material’s character  and choosing suitable grab.

Four rope crane grab is designed and manufactured by mature technology, every connecting joints’ liner bushing applies quality bearing steel, cutting edge plate is thicken, so the grab is more wear resistant and longer service life.

          

At the beginning of work, supporting rope lifts the grab to suitable position, then release open-close rope, the grab’s bucket will be forced to open under the acting force of bottom crossbeam’s self-weight, open action will not stop until collision blocks collide, so, the bucket be open to its limited dimension. During bucket’s open activity, the centre distance is increased between upper cross beam pulley and bottom cross beam’s support beam, at this moment, supporting rope falls down to place opening grab to bulk material stockpile. At last, open--close rope is tighten up, center distance between the upper cross beam pulley and bottom cross beam pulley is restored to the original position, thus material grabbing process is finished. The materials have been full filled y in bucket, supporting rope and open-close rope are lift together, whole grab be lift at the same time, and is moved to unloading place by grab crane, then open bucket to unloading all materials.

* Four rope crane grab/bucket technical data sheet:
No. Volume 
working duty Density
t/m³
pulley magnification wire rope
φmm
pulley Dia
φmm
grab selfweight
t
crane capacity
H(closeed)
Amm
H(open) 
Bmm
L(closed) 
Cmm
L(open)
Cmm
W(open)
Emm
remark
1 3 light ≤1 3 φ16 φ400 2.75 5 2922 3403 2200 3020 1820
2 2.5 light ≤1 3 φ16 φ400 2.73 5 2975 3514 2200 3120 1600
3 2 medium  1~2 5 φ16 φ400 2.71 5 3084 3547 2150 2985 1520
4 2 medium  1~2 5 φ16 φ400 2.73 5 3137 3658 2150 2985 1520 teeth
5 1.5 medium  1~2 5 φ16 φ400 2.5 5 2984 3429 1950 2750 1360
6 1.5 medium  1~2 5 φ16 φ400 2.57 5 3037 3540 1950 2860 1360 teeth
7 1 heavy  2~2.5 6 φ16 φ400 2.45 5 2855 3270 1850 2535 1150
8 1 heavy  2~2.5 6 φ16 φ400 2.5 5 2908 3381 1850 2635 1150 teeth
9 0.75 super heavy 2.5~3.3 6 φ16 φ400 2.3 5 2760 3144 1650 2340 1054
10 0.75 super heavy 2.5~3.3 6 φ16 φ400 2.32 5 2813 3255 1650 2460 1054 teeth
11 5 light ≤1 3 φ20 φ500 4.26 10 3795 4430 2820 3800 2050
12 4 light ≤1 3 φ20 φ500 4.24 10 3595 4153 2445 3431 2210
13 3 medium  1~2 5 φ20 φ500 4.38 10 3595 4153 2445 3431 1810
14 3 medium  1~2 5 φ20 φ500 4.42 10 3695 4332 2445 3431 1810 teeth
15 2 medium  1~2 5 φ20 φ500 4.25 10 3640 4127 2200 3251 1550
16 2 medium  1~2 5 φ20 φ500 4.29 10 3694 4268 2200 3251 1550 teeth
17 2 heavy  2~2.5 6 φ20 φ500 3.95 10 3640 4127 2200 3251 1550
18 2 heavy  2~2.5 6 φ20 φ500 4 10 3694 4268 2200 3251 1550 teeth
19 1.5 super heavy 2.5~3.3 6 φ20 φ500 3.78 10 3357 3814 2020 2969 1470
20 1.5 super heavy 2.5~3.3 6 φ20 φ500 3.82 10 3409 3955 2020 2969 1470 teeth
21 1 heavy super 2.5~3.3 6 φ20 φ500 3.46 10 3052 3445 1676 2280 1464
22 1 heavy super 2.5~3.3 6 φ20 φ500 3.5 10 3141 3578 1676 2280 1464 teeth
23 8 light ≤1 3 φ24 φ600 7.96 16 4545 5292 3205 4387 2370
24 7 light ≤1 3 φ24 φ600 7.54 16 4610 5359 3166 4530 2297
25 6 light ≤1  3 φ24 φ600 7.6 16 4610 5359 3166 4530 2000
26 6 light ≤1  3 φ24 φ600 7.69 16 4700 5490 3166 4530 2000 teeth
27 6 medium  1~2 5 φ24 φ600 7.77 16 4610 5359 3166 4530 2000
28 6 medium  1~2 5 φ24 φ600 7.86 16 4700 5490 3166 4530 2000 teeth
29 4.8 medium  1~2 5 φ24 φ600 7.66 16 4320 4948 2820 4068 2020
30 4.8 medium  1~2 5 φ24 φ600 7.82 16 4410 5080 2820 4068 2020 teeth
31 4 heavy  2~2.5 5 φ24 φ600 7.36 16 4320 4948 2820 4068 1770
32 4 heavy  2~2.5 5 φ24 φ600 7.52 16 4410 5080 2820 4068 1770 teeth
33 3.2 heavy  2~2.5 6 φ24 φ600 7.65 16 4175 4750 2600 3726 1781
34 3.2 heavy  2~2.5 6 φ24 φ600 7.75 16 4265 4880 2600 3726 1781 teeth
35 2.5 super heavy 2.5~3.3 6 φ24 φ600 6.88 16 4117 4642 2350 3431 1550
36 2.5 super heavy 2.5~3.3 6 φ24 φ600 6.98 16 4210 4772 2350 3431 1550 teeth
37 10 light ≤1  3 φ28 φ700 10.52 20 5103 5850 3500 5021 2496
38 10 light ≤1  3 φ28 φ700 10.66 20 5202 6029 3500 5021 2496 teeth
39 8 light ≤1  5 φ28 φ700 10.72 20 5103 5850 3500 5021 2096
40 8 light ≤1  5 φ28 φ700 10.86 20 5202 6029 3500 5021 2096 teeth
41 6 medium  1~2 5 φ28 φ700 10 20 4172 5455 3200 4557 2220
42 6 medium  1~2 5 φ28 φ700 10.2 20 4271 5634 3200 4557 2220 teeth
43 4 heavy  2~2.5 6 φ28 φ700 9.8 20 4583 5250 2900 4124 1890
44 4 heavy  2~2.5 6 φ28 φ700 10 20 4682 5430 2900 4150 1890 teeth
45 3 super heavy 2.5~3.3 6 φ28 φ700 8.85 20 4431 4903 2399 3822 1890
46 3 super heavy 2.5~3.3 6 φ28 φ700 9.05 20 4530 5083 2399 3822 1890 teeth

2. Two Rope Crane Grab

two rope crane grab is used under the integration of overhead crane, port crane, and electric winch, widely used in port, power station, yard, chemical factory, to grab all kinds of ore, coal, slag and so on, for loading, unloading, transportation and charging material.

On the winch, there are two ropes, one for supporting the whole grab in the air, the other for grab’s open and close. When the grab is fall down on the material, open-close rope is tightened up to catch and close loose material, at the same time, supporting rope is lift too, the grab is lift and transported to pointed position; then release open-close rope, grab is opened and loose material falls on right place.

          

3. Anti Leakage Crane Grab

In the processing of grabbing bulk material, some special material has good fluidity and with small internal adhesion and friction, easily side leakage from grab’s gap, for example: fertilizer, alumina and so on. Material leakage’s main parts is at the bucket’s horizontal cutting edge, so, need to design special anti-leakage crane grab.

At the beginning of work, supporting rope lifts the grab to suitable position, then release open-close rope, the grab’s bucket will be forced to open under the acting force of bottom crossbeam’s self-weight, until collision blocks collide, open will be stopped, so, the bucket be open to its limit dimension. At the bucket open activity, the centre to centre spacing is increased between upper cross beam pulley and bottom cross beam’s support beam, then supporting rope fall down to place opening grab to grabbing bulk material stockpile. At final, the open--close rope be tighten up, center distance between the upper cross beam pulley and bottom cross beam pulley is restored to the original position, thus material grabbing process is finished. The materials have been full filled y in bucket, supporting rope and open-close rope are lift together, whole grab be lift at the same time, and is moved to unloading place by grab crane, then open bucket to unloading all materials.

Remark: anti leakage crane grab’s pulley magnification should not less than 5, and grab body’s stiffness-processing and assembly-accuracy all need high requirements.

          


4. Multi-Jaw Crane Grab / Orange Peel Crane Grab

For multi-jaw crane grab/bucket, there are 4 jaw grabs, 6 jaw grab and 8 jaw grabs. There are also single rope multi-jaw grab, double rope multi-jaw grab, four rope multi-jaw grab, hydraulic multi-jaw grab and motor multi-jaw grab, five types.

Multi-petal crane grab mainly used for grabbing materials which in harsh environment, irregular and hard to grab, for example: waste, ore, scrap steel, aluminum ingot, limestone, gravel and other material for loading, unloading and shipment, this type grab wildly used in garbage dump, scrap yard, ports, mines and railways. (Motor grab cannot be used under water)

          

5. Electric Crane Grab 

Electric crane grab is mainly used to load and unload loose materials: ore, limestone, slag, pulverized coal, coke and so on, cannot launching operation.
Grab’s lifting-lowering motion depends on a single drum lifting mechanism or hanging on hook, open-close motion depends on the components fitted on grab’s head: motor, gear box, drum which can drive bottom cross beam to finish open-close operation.
When the grab works in outdoor, rain-proof devices should be applied, cannot be use in inflammable, explosive, acid and alkali vapor environments.


          

6. Motor Crane Grab

Motor crane grab be used for grabbing granular materials, such as ore, sand carbide, slag, ore power, coke, coal, loose clay, etc. Also, like electric grab, motor grab cannot be used underwater.

Motor crane grab’s lifting motion depends on a single drum lifting mechanism or hanging on hook, the grab is fitted with open-close mechanism itself in many types. Kingda crane motor grab’s open-close motion depends on electric hoist to finish which is installed inner the grab. Don’t like Four rope crane grab, there no upward pulling force when the grab is opened or closed, grab’s deadweight all be used for grabbing, so grabbing force is great, suitable for grasping material which is hard to grasp, such as ores.

7. Electric Hydraulic Crane Grab

Electric hydraulic crane grab is divided into multi petals electric hydraulic grab and double petals electric hydraulic grab.
Electric hydraulic orange peel crane grab mainly is used for loading and unloading irregular bulk cargo, such as scrap steel, pig iron, stone, etc. It is suitable for steel works , waste incineration treatment, ports, railways transit and other occasions.

Electric hydraulic double jaw crane grab can be used for loading and unloading irregular bulk cargo of all kinds of crane, maximum particle size should be less than 100 mm, especially on container crane, marine crane and multi-functional crane, which can greatly improve crane’s comprehensive performance.

Not matter for multi jaw or double jaw crane grab, the grab is fitted with electric hydraulic system itself to complete its open-close action, comprehensively apply for electrical hydraulic technology, mechanical technology, system design, high level automation, high efficiency and energy saving, with higher excavating and closing ability than same specification’s rope grab.
         
* multi-jaw electric hydraulic grab technical data sheet:
No. Volume
working duty Density   
 t/m³
power 
 kw
grab selfweight    t crane capacity   t  H (closeed)
Amm
L(closed) 
Cmm
H(open) 
Bmm
L(open) 
 mm
jaw Number remark
1 2 heavy 2.5 22 4.5
2 5 medium 1.35 37 3.6 10 3381 2760 2820 3930 6 complete closed
3 5 light 0.5 18.5 3.1 10 3381 2760 2820 3930 6 complete closed
4 8 light 1 30 5.1 16 3749 3166 3000 5000 6 semi-closed
5 4 light 1 18.5 4 10 3100 2635 2545 4025 6 semi-closed
6 6.3 light 1 30 5.9 16 4520 3090 3880 4860 6 semi-closed
7 10 light 1 45 7.48 20 4530 3280 3650 5150 6 semi-closed
8 12 light 1 45 7.6 20 3988 3717 3262 5489 6 semi-closed
9 8 light 1 30 5.2 16 3789 3167 3025 4965 6 semi-closed
10 8 medium 1.5 37 8.5 20 3560 3365 2790 5080 6 complete closed
11 1.5 heavy 1.5 22 3.78 8 2937 2040 2668 3350 6 complete closed
12 1.5 medium 0.8~1.4 15 2.5 5 3326 1896×1600 3279 2230×1600 2 teeth
13 4 medium 1.1~1.3 18.5 3.4 10 3100 2200×2100 3910 2930×2100 2
14 3 heavy 1.7~2.5 22 3.5 12 2957 2035×1826 2763 2582×1826 2
15 2.5 heavy 1.7~2.5 22 3.5 12 2997 2035×1826 2803 2582×1826 2
16 2.5 medium 1.0~1.3 15 3.11 10 3123 2023×1822 2953 2652×1822 2 teeth
17 5 medium 1.0~1.3 22 4.7 16 3560 3420×2400 3230 3050×2400 2 teeth
18 3.2 medium 1.0~1.3 15 3.4 10 3059 2668×2000 3101 2945×2000 2

8. Electric Single Monorail for Rope Crane Grab

Electric single monorail for rope grab is an overhead lifting and transporting equipment, don’t occupying many production areas, completely relay on overhead monorail to finish material’s transportation, and carry out open-close and lifting at the same time.

This grab can b operate easily, with reliable performance and high efficiency, is widely used in ports, buildings, construction sites, workshops, coal yards, warehouses, slag pools, etc. The grab can be operated on the ground by pendant, in the air with cab, and also can be operated by wireless radio (work principle same as Four rope crane grab).

          

9. Single Rope Suspended Crane Grab

Single rope suspended crane grab is divided into single rod and double rods, its usage and operation are the same, but this type grab cannot be open in the air.
Suspended crane grab is used when there is lifting drum only (single hook) in any kinds of general crane, suitable for grabbing various loose materials, and most suitable for grabbing under the water.


 
No. Volume 
 m³
working duty Density   
t/m³
pulley magnification wire rope
φmm
pulley Dia
φmm
grab self weight 
t
crane capacity 
 t 
H (closeed)   Amm H(open) 
 Bmm
L(closed) 
Cmm
L(open) 
Cmm
W(open) 
 Emm
1 0.3 light 1.2 2 φ13 φ200 0.8 2 2960 3900 1100 1385 620
2 0.5 light 1.2 2 φ15 φ200 1.1 3 2960 3900 1100 1385 920
3 0.75 heavy 2.2 2 φ13 φ240 1.8 5 2785 5000 1550 1770 1232
4 0.75 super heavy 2.6 2 φ13 φ240 2.05 5 2785 5000 1560 1770 1232
5 1 heavy 2.4 2 φ16 φ240 1.8 5 2789 4500 1600 1773 1280
6 1 light 1.2 2 φ16 φ190 1.6 5 2779 4500 1460 1764 1260
7 1.5 heavy 2 2 φ16 φ300 2.4 5 3401 5400 1650 2447 1350
8 1.5 super heavy 2.8 2 φ18 φ300 3 10 3426 5400 1650 2507 1700

10. Stainless Steel Crane Grab

Stainless steel crane grab is customized specially for brewing in winery or food factory, used for grabbing and transporting koji sauce, sauce residue and so on.
For workshop and processed food, stainless steel grab is clean processing by using stainless steel crane grab, and greatly reduces labor number.

Stainless steel crane grab also can be divided into four ropes stainless steel grab, double ropes stainless steel grab, single ropes stainless steel grab and electric stainless steel grab. It is the same as other structure grab, different feature is: stainless steel grab’s processing material must be stainless steel, but, the same working principle.
          


11. Loose material specific gravity/density
 
Material  specific gravityt/m³ Material  specific gravityt/m³
anthracite 0.7~1.0 pyriteblock 2~2.6
bituminous coal 0.8 manganese ore 1.7~1.9
lignite 0.6~0.8 magnesiablock 2.2~2.5
peat 0.29~0.5 powder magnesia 2.1~2.2
peat(wet) 0.55~0.65 copper mine 1.7~2.1
coke 0.36~0.63 copper concentrate 1.3~1.8
charcoal 0.2~0.4 lead concentrate 1.9~2.4
anthracite dust 0.84~0.89 zinc concentrate 1.3~1.7
bituminous coal fines 0.4~0.7 lead-zinc concentrate 1.3~2.4
plumbago 0.45 ore sintering caking 1.7~2.0
magnetite 2.5~3.5 bump sintering caking 1.4~1.6
hematite 2.0~2.8 lead sintering caking 1.8~2.2
limonite 1.2~2.1  lead-zinc sintering caking 1.6~2.0
zinc dust 0.7~1.5 big limestone block 1.6~2.0
pyrite cinder 1.7~1.8 medium limestone block 1.2~1.5
lead-zinc briquette 1.3~1.8 small limestone block 1.2~1.5
pyrite pellet 1.2~1.4 quicklime  1.7~1.8
open-hearth slag(coarse) 1.6~1.85 rubble 1.32~2.0
blast furnace slag 0.6~1.0 dolomite(block) 1.2~2.0
lead-zinc liquid disintegrating slag 1.5~1.6 small piece dolomite 1.8~1.9
dry coal ash 0.64~0.72 gravel 1.5~1.9
coal ash 0.7 gravel (small block) 0.7~1.5
coarse sand(dry) 1.4~1.9 gravel(wet) 1.7
coarse sand(wet) 1.4~1.65 cement 0.9~1.7
fine sand(wet) 1.8~2.1 hydrated lime(power) 0.5
molding sand 0.8~1.3 hydrated lime 2
 
material type grabbing material material densityt/m³
light coke, slag, cereal, potato, cement, soil and gravel, clay, brickbat, lime, mid-size anthracite 0.5~1.2
medium peat, big-size anthracite, compacted coal, clay, limestone, breakstone, salt, gravel, fragment of brick, bauxite, tablet iron oxide skin, cement, brick and sand in water, etc.  1.2~2.0
heavy limestone, heavy clay, medium-small size mineral, lead-zinc mineral, hard stones, stick column iron oxide iron ore   2.0~2.6
super heavy big size ore, big size manganese ore, seated and clumped lead-zinc power  2.6~3.3
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