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 m³	working duty	Density t/m³	pulley magnification	wire rope φmm	pulley Dia φmm	grab selfweight t	crane capacity t	H(closeed) Amm	H(open) Bmm	L(closed) Cmm	L(open) Cmm	W(open) Emm	remark
No.	Volume m³	working duty	Density t/m³	pulley magnification	wire rope φmm	pulley Dia φmm	grab selfweight t	crane capacity t	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	heavysuper	2.5＞~3.3	6	φ20	φ500	3.46	10	3052	3445	1676	2280	1464
22	1	heavysuper	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 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 m³	working duty	Density t/m³	power kw	grab selfweight t	crane capacity t	H(closeed) Amm	L(closed) Cmm	H(open) Bmm	L(open) Cmm	jaw Number	remark
No.	Volume m³	working duty	Density t/m³	power kw	grab selfweight t	crane capacity t	H(closeed) Amm	L(closed) Cmm	H(open) Bmm	L(open) Cmm	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 selfweight t	crane capacity t	H (closeed) A mm
No.	Volume m³	working duty	Density t/m³	pulley magnification	wire rope φmm	pulley Dia φmm	grab selfweight t	crane capacity t	H (closeed) A mm
1	0.3	light	1.2	2	φ13	φ200	0.8	2	2960
2	0.5	light	1.2	2	φ15	φ200	1.1	3	2960
3	0.75	heavy	2.2	2	φ13	φ240	1.8	5	2785
4	0.75	super heavy	2.6	2	φ13	φ240	2.05	5	2785
5	1	heavy	2.4	2	φ16	φ240	1.8	5	2789
6	1	light	1.2	2	φ16	φ190	1.6	5	2779
7	1.5	heavy	2	2	φ16	φ300	2.4	5	3401
8	1.5	super heavy	2.8	2	φ18	φ300	3	10	3426

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 gravity（t/m³）	Material	specific gravity（t/m³）
anthracite	0.7~1.0	pyrite（block）	2~2.6
bituminous coal	0.8	manganese ore	1.7~1.9
lignite	0.6~0.8	magnesia（block）	2.2~2.5
peat	0.29~0.5	powery 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
charcial	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 singtering 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	mediu 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
moulding sand	0.8~1.3	hydrated lime	2

Material type	Grabbing material	Material density（t/m³）
Material type	Grabbing material	Material density（t/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, mediu-small size mineral, lead-zinc minral, 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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