Japan Asphalt Finisher: Commonly, they are known as Paver vehicles, paver machine. It is a self-propelled construction equipment, used for lay paving on roads, bridges, parking lots and other area. Also, it lays the asphalt flat and provides minor compression before it is compressed by a roller. It consist of two major components i.e. a tractor and a screed.
How they work?
The tractor helps in the forward movement and in distribution of the asphalt, it consist of hydraulic drives, controls, engine, drive wheels or tracks, receiving hopper,feeder conveyors, distribution augers. The screed levels and shapes the layer of asphalt, it is dragged by the tractor and includes the leveling arms, endplates, vibrators, moldboard, slope sensors and controls. While during the operation, a dump truck filled with asphalt up to the front of
the paver and slowly discharges its load into the paver’s hopper, The pavers move forward and the feeder conveyors make the movement of asphalt towards the rear of the paver, and the distribution augers push the asphalt outward to the desired width. The screed then levels the layer of asphalt and partially compacts it to the desired shape. A heavy, steel-wheeled roller follows the paver to further compact the asphalt to the desired thickness.
It was developed by Barber Greene CO., which actually manufactured material handling systems. In year 1929, the chicago testing laboratory approached them to use their material loaders to construct asphalt roads. It traveled on a set of steel rails and included a combination loader and mixer to proportion and blend the components before spreading the asphalt evenly over the road surface. The crawler tracks, replaced the rails soon and the first production paver came off the Barber-Greene line in 1934. Rapidly this new machine became popular among road builders because it allowed them to place asphalt more quickly and with greater evenness. During the late 1950s, hydraulic drives replaced mechanical drives in pavers to give the operator even smoother control. Today, almost all asphalt is placed using paving machines.
Almost all of the components of paving vehicle is made up of steel. The mainframe of the tractor is fabricated from the heavy -gauge steel plate. The feeder conveyor is made of heavy-duty chain with forged steel sections, and are called flight bars. Screed is fabricated from steel tubing, plate and channel, distribution augers are made of cast Ni -hard steel andthe engine covers and access doors are formed from steel sheet. Rubber -tired pavers have two large inflatable drives tires and four or more smaller solid rubber steering tires. Synthetic rubber track are used to mold to rubber-tracked pavers with several internal layers of flexible steel cable for coating. All the bogie wheels are made of rubber-coated wheels.
Different manufacturers of paving vehicles offers different sizes and models. Typically, the engine horsepower ranges in the 3-20hp (2-15 kw) for smaller, dragged pavers, and may be in the 100-250 hp (75-188) range for larger, or self propelled pavers. Likewise, the other construction equipment, diesel is used as the fuel for engines. Most larger, self-propelled pavers are about 19-23 ft (5.8-7.0 m) long, 10 ft (3.1 m) wide, and 10 ft (3.1 m) high. They weigh about 20,000-40,000 lb (9,090-18,180 kg) depending on the hopper capacity, engine size, and type of drive system.
The typical rate of asphalt placement is 100-300 ft/min (31-92 m/min). The standard paving width is 8-12 ft (2.4-3.7 m) up to a maximum width of 40 ft (12.2 m) with the use of screed extensions on some machines. The maximum paving thickness on a single pass is 6-12 in (152-305 mm). Options include lighting packages, manual and automatic screed extensions, and various sensors and controls to alter the grade (fore-aft dimensions) and slope (side-to-side dimensions) of the layer of asphalt.
The asphalt pavers consists of many components part, so they are assembled in sequence wise. Not all the parts are manufactured at same plant, some of them shipped from other places. And other than that parts are fabricated in the assembly plant, all the parts are given a primer coat. The parts are stored in the warehouse and are brought to various workstation or areas as needed. Both the tractor and the screed are assembled separately, the process of assembling the tractor starts by placing the mainframe on air-flotation pallet. Allowing the heavy tractor to float on a thin cushion of air, and so it can be easily pushed from one workstation to another with the help of guide rails in the floor. The screed is assembled in a single area and does not move from one workstation to another.
Here is a general sequence of operation for the assembly of an asphalt paver:
- Fabricating the tractor mainframe.
- Fabricating the tractor mainframe.
- Assembling the screed.
- Testing the tractor.
- Finishing the paver.
- Testing the screed.
It is necessary for all suppliers to check thoroughly and certify all the components before the shipping process. At regular interval, a thorough dimensional and metallurgical inspection is given to ensure high quality. So, the air-operated wrenches used to tighten critical fasteners are checked and determined to make sure they are delivering the proper torque. The tractor and screed are machine-tested separately in addition to several visual inspections by human operators, and then checked again once the tractor and screed are coupled together for delivery.
Importance of Asphalt Pavers
As an area is paved for the concern of protection, if the surfaces are not paved with brick paving or concrete paving and becomes responsive to the other elements. And it becomes horror to fix it when wind and rain weathers down a sandy surface over the time. Gradually, the soil is washed away the foundation of these structures may be compromised which may pose a safety risk. In that case, paving is the only solution when you can be assured regarding the safety and protection of that kind of area.