785mm Spherical Grab 785mm Spherical Hammer Grab Used Inside of 880/800mm Double
详细信息
785mm spherical grab 785mm spherical hammer grab used inside of 880/800mm double wall casing for bored pile foundation work785 mm double rope spherical grab 785mm spherical hammer grab used inside of 880/800mm double wall casing used with hydraulic casing oscillator
785mm spherical grab 785mm spherical hammer grab used inside of 900/820mm double wall casing for bored pile foundation work
785 mm double rope spherical grab 785mm spherical hammer grab used inside of 900/820mm double wall casing used with hydraulic casing oscillator
1065mm spherical grab 1065mm spherical hammer grab used inside of 1180/1100mm double wall casing for bored pile foundation work
1065mm double rope spherical grab 1065mm spherical hammer grab used inside of 1200/1120mm double wall casing used with hydraulic casing oscillator
1300mm spherical grab spherical hammer grab used with hydraulic casing oscillator for cased bored pile for hard soil conditions
1600mm spherical grab spherical hammer grab used with hydraulic casing oscillator for cased bored pile for hard soil conditions
We produce several models of hammer grab for crane lifting used for cased and uncased borehole, our hammer grab have single rope type hammer grab ,and double rope hammer grab
Spherical grab is used on jobs where drilling has to be carried out free of vibrations and or where partially cased or uncased drilled shafts are to be produced, the high deadweight in conjunction with the high closing force ensures a high efficiency
Tianjin huachang xingye technology co ltd fabricate spherical grab operates through a double rope function. They have a strong grab force that is best for excavating hard soil and even soft rock
Double rope spherical grab with high close force suitable for vibration free boring in semi hard and hard soil conditions
Hammer grab with high clamping force, particularly suitable for drilling of holes in rocky soils and for working under water load
SPHERICAL GRAB for bored pile 800-3000mm
spherical Hammer grab is the most important tool used in piling and determines the progression of the drilling. In addition to the maximum grabbing capacity, unloading is quick and easy. The stresses of the whole structure are relieved and very strong
Surfaces exposed to wear are made of NM400 material. Chassis and arms that require strength are made material. Guides and holders are made of Q355 material.
We have two different spoon systems as below: Pulley Type X-Linked Type Spherical Type
| Casing size mm | L MM | L1 | B | B2 | weight |
| 2000/1880 | 4600 | 5700 | 1650 | 2200 | 17000 |
| 2500/2380 | 4600 | 6000 | 1750 | 2200 | 21000 |
| 2800/2680 | 4600 | 6200 | 1750 | 2200 | 23000 |
Using a spherical grab in tandem with a casing oscillator is the definitive standard for the "All-Casing Method" (or Benoto Method). This powerhouse combination is specifically deployed for drilling deep, large-diameter bored piles in highly unstable, collapsible, or demanding ground conditions (such as loose sands, gravels with heavy cobbles, and water-bearing strata).Here is a technical breakdown of how these two components work together, their operational sequence, and why they are paired.The Roles of Each Component1. Casing OscillatorThe casing oscillator sits at the surface, anchored either to the ground or to a host crane/drilling rig. Mechanism: It clamps onto the heavy steel casing strings and uses high-torque hydraulic cylinders to oscillate (rotate back and forth in an arc) while simultaneously applying a massive vertical downward force. Function: It drives the casing deep into the ground ahead of or simultaneously with excavation, creating a continuous structural shield that prevents the borehole walls from caving in. 2. Spherical Grab (Hammer Grab) Suspended from a duty-cycle crawler crane positioned directly over the casing oscillator, the spherical grab is the primary excavation tool.Mechanism: Unlike standard cylindrical or rectangular bored pile grabs, a spherical grab features heavy, rounded, cup-like jaws (spherical shells) often outfitted with high-strength replaceable teeth. It is typically operated via a double-rope system (one for lifting/lowering, one for opening/closing) or hydraulically.
Function: It drops inside the casing to dig, break up, and extract the soil.Why the Spherical Grab is Paired with an Oscillator Perfect Geometry Match: The spherical shape of the grab jaws matches the inner curvature of the circular steel casings perfectly. This allows the grab to clean right up to the casing walls without damaging the inner face or getting wedged.High Splitting and Closing Forces: When driving casings into dense gravelly soil, boulders, or cohesive clays, standard augers or light grabs fail. The massive dead weight (often 7 to 15+ tons) and the high closing torque of a spherical grab allow it to chip away at hard layers and securely trap loose cobbles or soupy materials. Multi-Clamping Capability: Because the double-rope or hydraulic spherical grab can open and close repeatedly at the bottom of the hole, the operator can repeatedly punch and grab to break up stubborn ground before hoisting it out. Step-by-Step Operational Sequence The operation is a continuous cycle of driving and digging:
[Drive Casing] [Drop Spherical Grab] [Excavate Soil] [Repeat to Depth] Step 1: Driving the Starter Casing The casing oscillator clamps the first section of casing (the starter casing, fitted with a hardened cutting shoe at the bottom). The oscillator begins twisting and pushing it into the ground. Step 2: Excavation inside the Casing The spherical grab is lowered in the open position down the center of the casing. It plunges into the soil under its own weight. The operator closes the spherical jaws, biting a huge volume of earth or rock fragments, and hoists it out to discharge. Important Geotechnical Note: To prevent a "piping" failure or boiling at the base (where high hydrostatic pressure forces loose sand upward into the casing), a positive water head is strictly maintained inside the casing during excavation. The hydrodynamic design of the spherical grab allows it to fall rapidly through this water without excessive drag. Step 3: Advancing the Borehole
As the grab clears out the inside, the casing oscillator continuously presses the casing further down. Once a casing section is fully driven, a new section is bolted or welded on top, and the process repeats until the target design depth is achieved. Step 4: Concreting and Casing Extraction Once the design depth is reached and the base is cleaned, the reinforcement cage is lowered. Concrete is poured through a tremie pipe. As the concrete rises, the casing oscillator reverses its vertical function-using its massive lifting cylinders to oscillate and extract the casing sections one by one.
