HYDRAULIC VIBRATORY GLOSSARY
The BRUCE Hydraulic Vibro Hammer Standard Glossary of Terminology has specially been prepared with the object of unifying the various technical terms and expressions targeted for majority members of construction conductors on sites who are being involved with BRUCE Vibro Hammer to be operated at the various different Vibro operation taking place through the world. We wish that this standard would be helpful for the customers being familiar with BRUCE.
It is consisting of three main parts of a shell, a Bladder and a oil port and is placed inside the Power Pack close to a Relief Block.
The Accumulator here in the Power Pack is relatively small size containing less than 10 liters of Nitrogen gas to take its role as an shock absorber mainly protecting a sudden stop the Engine mainly caused by overload the Engine.
This is because that, for example, the present pressure is pushing at 150kg/㎠, then, it will be compensate to be 200kg/㎠ when Operating Pressure goes up 200kg㎠ in the same value that oil goes from V/V to an accumulator, then finally oil can be drained to tank when the Engine stops
It is the width of periodic vibration measured in the Vibro.
The Amplitude is a key factors for Vibro Hammer to be selected and it must be higher than sand and also it should be between 3~6mm for clay soil.
General description of Amplitude is that it should be between 6~12mm. The Amplitude will travel vertically to shear the soil away per vibration.
It is also called as ‘Raked Pile’.
A pile driven on angle driving in an angle to the vertical, and it is normally used for counteracting its horizontal force acting on vertical piles
It is called as ‘Steel Tube Pile’ or ‘Tubular Pile’ by many workers on sites, but the leading reason for calling a Caisson Pile is that it ’
s for typically in the Caisson foundation by using the Vibro Hammer operation.
This pile is manufactured in seamless spirally welded or well lap-welded and is normally installed by top driving but in difficult ground conditions
and also it can be installed by a combination of drill and drive. This pile is born as a watertight retaining structure used for,
for example, to work on the foundation of a bridge pier, for the construction of concrete dam or for the repair of ships.
These are constructed such that the water can be pumped out, keeping the environment dry and is sunk into the ground to some desired depth
and then filled with concrete thus forming a foundation that this is because Caissons can be floated to the job site.
The types of Caissons are varied like Box type, Excavated type, Open type, Pneumatic type and Caisson Sheet Pile.
It is one of main part of Vibro Hammer attached to on bottom of Vibro body to conduct a practical Vibro operation after it grabs the piles.
The clamp contains two gripping jaws, one is “fixed” and one is “movable”.
A large hydraulic cylinder in the Clap operates the moveable jaw with up to designed power tons of clamping force depending on clamp pump relief pressure.
The jaws open and close by turning a switch on the remote control pendant, or may be operated by turning the switch at the main control panel, mounted behind one of the doors on the power unit.
The check valve automatically operates the clamp flows either the direction Close or Open.
Clamp types provided by BRUCE are varied, among them the Universal type, which is also called as ‘Single Clamp’ and Caisson Clamp which is also called as ‘Double Clamp’
are the most representing Clamp released by BRUCE.
It is important key factor that decides the Vibro performance.
It is generated by rotating Eccentric Weights inside the Gearbox shaped like a half moon and it is connected with other components by Gears and Shaft to create the moment.
A small increased speed can turned out a large increasingly developed Centrifugal Force and this force is generally measured in tons by BRUCE Vibro Hammer.
are the most representing Clamp released by BRUCE.
It is called as ‘Clamping Force’ by BRUCE.
It is the area of piston rod head of the clamp multiplied by the available Clamp Pressure of the Power Pack.
The Clamp Force is very important to the life of Jaws of the Clamp.
This is the first key factor in Vibro performance.
The Eccentric Moment must create big enough Amplitude to exceed the elastic range of various soils.
If Eccentric Moment is bigger, the Amplitude will be automatically the same in Vibro performance.
The Eccentric Moment is described the effectiveness of a force to produce rotation about an axis.
It is the value that is equal to the weight of the Eccentric Weights multiplied by the distance from the center line of gravity to the center
line of rotation and Then multiplied by the total number of Eccentric Weights used in the Gearbox.
It is also called as ‘Elastomer Rubber’ on just’ Rubber’ by many others.
When upward vertical vibrations created by the rotating Eccentric Weights in the Vibro, the Elastomers attached on the Suppressor Housing absorbs the vibration imparted by the Vibro and prevent damage to the Crane boom.
It should be periodically inspected when Vibro is being used regularly.
It is aimed at relatively small Vibros can be mounted on the Excavator to enhance the mobility to be light and fast with agile transportation to the task compared with Crane Suspended Vibro.
It has no additional Power Pack, in stead, It is necessarily to pick up the Hydraulic source from an exacting Excavator the customers owned.
Excavator Mounted Vibro provided by BRUCE boasts a high punctuality rate to the Vibro task with hydraulically rotating at 360 degrees to make piles positioned for more precise method of operation.
Adding an Extra Weight to the Static Weight of Vibro can increase the Vibro performance resulting in more deeper and faster penetration especially, when the Vibro need to vibrate a firm clay soil although it is less effective in sand.
This is because the Centrifugal Force must overcome its resistance under the pile, where the friction of clay soil would be reduced by the Amplitude.
In general, unfavorable result can be brought in sand when a total static weight of Vibro is more than the Dynamic Weight of Vibro.
It is also called as’ Normal Frequency Vibro’ or ‘Standard Vibro Hammer’ by many others among Vibro manufacturing company.
The Frequency range of Fixed Moment Vibro Hammers are specified on the average between 1600~2200 vpm to conduct a standard Vibro work.
Regardless of Fixed Moment type or Variable Moment type, all the Vibro Hammer is consisting of three main components, which are Suppressor Housing, Gearbox Assembly and Clamp Assembly.
The Eccentric Weights In the Gearbox rotates in a vertical plane to create vibration driven by hydraulic motors mounted on Gearbox Assembly where
two of both are connected each other to keep them a proper synchronization that creates vertical vibration.
The vibration can be transmitted into pile being driven by means Clamp
In physics, it means that the number of cycles or completed alternation per unit time of a wave or oscillation, but in Vibro terms, it is the vibration per minute (vpm) and speed of rotating eccentric weights
It means that the overall weight of the Vibro Hammer in Combination with its Frequency and Centrifugal Force that helps to drive a pile
Output horsepower of the hydraulic motors is equal to the actual gallons per minute of hydraulic oil being delivered multiplied by the maximum relief setting of the hydraulic system.
It is important when reviewing hammer specifications that the diesel engine horsepower is capable of providing more power than is required to achieve the required hydraulic horsepower.
Without this horsepower available, it is not possible to maintain frequency to obtain maximum driving forces.
t is the amount of pull Suppressor can handle before engaging in safety stops.
More is better but the Crane must be able to apply pulling at radius and it is measured in tons.
It is also called as ‘Static Weight’ by others the weight of non-vibrating parts of Vibro that are normally Suppressor, Elastomers and added any extra weight and it is measured in kg.
In physics, Resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others.
Frequencies at which the response amplitude is a relative maximum are known as the system’s Resonance frequencies .
Looking at the Vibro operations, Resonance normally occurs when getting the Vibro Hammer starting and stopping moment by the movement of hydraulic motors
in the Vibro that are connected with two or more gears inside the gear box to rotate and to create such as kinetic energy , which is ‘Centrifugal Force’
in Vibro terms, forming some specific type of frequency from cycle to cycle.
Resonance phenomena occur with all types of Vibro Hammer but the Vibros from BRUCE can control its Resonance effect from starting and stopping the Vibro by reducing the Engine speed in order not the Vibro transfers energy radically.
In the Vibro Hammer industry, the resonance free Vibro is equipped with Variable Moment and this Vibro Hammer can have a lot of advantages then Fixed Moment Vibro, in terms of driving Vibro even in the very urbanized area.
In general, sand and soft soil are especially suited for Vibro operation and well graded sand is much easier to vibrate then uniform sand.
Round grains are easier than sharp sand and dense sand has higher penetration resistance than loose sand requiring larger Vibro Hammers with higher Centrifugal Force to overcome the resistance.
Clay with firm consistence is less suited for vibration and available Amplitude is the major criteria for the ability of Vibro to select the piles within planned project.
Vibrating in bigger stones and rocks are impossible to Vibro, in the meanwhile, the higher the water content in the soil, the easier it is to vibrate the pile and dry soil have higher penetration resistance than saturated soil that will require larger Vibro Hammer than it estimated at the early stage for Vibro operation
It is literally a total weight of Vibro that included firstly the Vibro itself plus typically a half the weight of Hydraulic Hoses and additional extra weight or special additions and it is measured kg.
It is also called as ‘Dynamic Weight’ by others. It is a vibrating parts of Vibro plus pile weight of any soil sticking on pile.
It is measured in kg and it is a important factor creating the Amplitude
Resonance Free Vibro fells on this Vibro.
The Frequency range of Variable Moment Vibro Hammers are specified on the average 2300 vpm to conduct its Vibro work.
When this Vibro is started and stopped, it has no Amplitude or Moment are created because this is accomplished with the use of two sets of Eccentric Weights that gives one set is apposing the other set during the secession of start up and stopping.
These Eccentric Weights are, then phased in and out of time each other during the operation creating Amplitude or Eccentric Moment.
This infinite Amplitude control allows for operator to minimize the radial vibration in the near native soil and to maximize the ability of pile by limiting the vibration nearby.
This result can lead the Suppressor creates no Crane line vibration known as Resonant Vibration which is commonly believed to occur for a certain Vibro.