Excavators are powerful machines that are essential for construction and excavation work. One of the key components of an excavator is the turntable, also known as the swivel or swing system.
This mechanism allows the upper and lower parts of the excavator to rotate in both directions, enabling the machine to reach different areas without having to move its tracks.
But how does this complex system actually work? In this article, we’ll take a closer look at the inner workings of an excavator turntable and explore the different components that make it possible.
So buckle up and get ready to dig deep into the fascinating world of excavator technology!
How Does An Excavator Turntable Work
The turntable of an excavator is a complex system that connects the upper and lower parts of the machine through a center shaft and an outside housing. The center shaft has holes bored into it, which direct hydraulic fluid to specific channels or inner barrels created by the shaft and the housing.
This design allows hydraulic fluid to flow from the center shaft, through the inner barrels, and in or out of a specific hole in the housing. A bearing or multiple bearings allow the shaft to spin freely from the housing, while seals at each end of the inner barrels contain the hydraulic fluid.
The lower and upper halves of the excavator are able to rotate in both directions and even multiple times around the center point of the turntable under the power of the hydraulic system. This allows for greater flexibility and maneuverability when working on construction or excavation projects.
The Basics Of Excavator Turntables
Excavator turntables are typically attached to the undercarriage of the machine with a large bearing. The inner race is usually attached to the undercarriage, while the outer race is attached to the excavator. The races are separated by balls or rollers, depending on the type of bearing used.
Gear teeth are usually cut into the inner race, and a transmission (usually planetary) has a large output pinion that engages these gear teeth. When the transmission turns the pinion, the excavator rotates on the bearing.
The swing transmission is attached to the excavator frame, and the swing motor drives the transmission. The swing motor receives oil from a control valve and rotates. The gearing within the transmission reduces the high speed, low torque output of the hydraulic motor into low speed, high torque required to swing the excavator.
Usually, a mechanical brake is provided as a parking brake when the machine is not swinging. Additionally, the motor is often used to dynamically stop the machine.
It’s important to note that there are variations in excavator turntables, both past and present. However, in general, they function in a similar way by picking up sound vibrations created by a vinyl record and turning them into an electronic signal that can be amplified. Keeping the turntable clean and in good shape is crucial for optimal performance.
Regular inspection and maintenance of excavator attachments, including rotary gear, is necessary to prevent abnormal sounds during rotation and ensure proper lubrication. The lubrication period for swing bearings should be set at every 250 hours, which may differ depending on job site conditions.
Understanding The Components Of The Turntable
To understand the components of the turntable, it is important to note that there are different names for this system, including slewing rings, turntable bearings, and slewing bearings. The turntable is made up of a housing and a center shaft, which are connected through a bearing or multiple bearings. The center shaft has holes bored into it, which direct hydraulic fluid to specific channels or inner barrels created by the shaft and the housing.
The inner barrels allow hydraulic fluid to flow from the center shaft and in or out of a specific hole in the housing. Seals at each end of the inner barrels contain the hydraulic fluid and prevent leaks. The bearing or bearings allow the shaft to spin freely from the housing, which enables the upper and lower halves of the excavator to rotate in both directions.
The turntable is an essential component of an excavator, as it allows for greater flexibility and maneuverability when working on construction or excavation projects. It is important to note that different manufacturers may have variations in their turntable design, but the basic components remain the same. Proper maintenance and inspection of the turntable is necessary to ensure its longevity and performance.
The Role Of Hydraulic Systems In Turntable Functionality
Hydraulic systems play a crucial role in the functionality of an excavator turntable. The hydraulic fluid that flows through the excavator swivel is what powers the rotation of the upper and lower parts of the machine. The hydraulic system is able to provide the necessary force to move the excavator’s heavy components, such as the boom and bucket, with ease.
The design of the excavator swivel allows for hydraulic fluid to flow through specific channels or inner barrels, which are created by the center shaft and outside housing. This design ensures that the hydraulic fluid flows smoothly and efficiently, providing the necessary power to rotate the turntable.
The use of bearings also plays a critical role in the functionality of the hydraulic system. The bearings allow the center shaft to spin freely from the housing, reducing friction and wear on the system. Seals at each end of the inner barrels also help to contain the hydraulic fluid, preventing leaks and ensuring that the system operates smoothly.
How Turntables Allow For Precise Maneuvering
One of the key benefits of the turntable on an excavator is the ability to make precise maneuvers. The turntable allows the operator to rotate the upper part of the machine in any direction, without having to move the entire excavator. This is especially useful when working in tight spaces or around obstacles.
The turntable also allows for smooth and controlled movements, as the hydraulic system can adjust the speed and direction of rotation as needed. This is important when performing delicate tasks, such as digging near underground utilities or working on a slope.
In addition, some excavators come equipped with a guideline function or intelligent automation that allows for even more precise maneuvering. With the guideline function, the operator can specify the exact route of the excavator and see a finished towing curve before making any movements. The intelligent automation even allows the machine to find its destination on its own, without the need for manual control.
Maintenance And Repair Of Excavator Turntables
Proper maintenance of an excavator turntable is crucial to ensure that it continues to function properly and avoid costly repairs. Here are some tips for maintaining and repairing excavator turntables:
1. Grease regularly: Regular greasing of the fittings around the bearing’s circumference at intervals recommended in the operator’s manual can help prevent bearing failure.
2. Purge with grease: Pumping grease into the bearing until old grease squeezes past the seal can help carry any contaminants out of the bearing.
3. Inspect the grease: Rubbing some of the purged grease between your thumb and forefinger can help detect any grit or metal chips, which may indicate a bearing problem.
4. Honor load charts: Even slight overloads can cause dimpling in the bearing race, which can worsen with subsequent loads and eventually lead to failure.
5. Avoid repetitive, heavy loads: Lifting with the boom and undercarriage in the same position can put a dimple in the bearing race close to the uneven load. Changing the angle of approach from job to job is recommended.
6. Predict failure and repair the bearing: If turning torque increases substantially or if you notice a clicking or grinding noise when rotating the structure, greasing the unit and having some of the purged lubricant analyzed for wear metals is recommended. Play or clearance in the bearing may indicate a problem and can show up as a lack of ‘stiffness’ in the extended boom.
7. Repair before it fails: Well-maintained bearings can usually be repaired at less than half the cost of buying a replacement, if it is repaired before it fails.
By following these maintenance tips, excavator turntables can be kept in good working condition, and costly repairs can be avoided. It is important to note that even with proper maintenance, bearings will eventually become worn out, so regular inspections are recommended to detect any issues early on.
Innovations In Turntable Technology For Increased Efficiency And Safety
With the advent of new technology, excavator turntables have become more efficient and safer to use. One such innovation is the D-Ecopower system, which features an electronically controlled pump, a closed-center main control valve, and nine sensors that electronically detect and control the precise amount of hydraulic oil required to perform a task. The hydraulic system output requirements are optimized with engine horsepower, resulting in reduced fuel consumption and improved productivity.
Another technology that has been developed for excavator turntables is the Smart Power Control. This technology is implemented through two systems, variable speed control, and pump torque control, that work together to improve efficiency while maintaining productivity. Smart Power Control can save as much as 5-7% in fuel consumption and provides improved feedback through the controls, resulting in an outstanding level of operator comfort and much smoother machine management.
Cameras have also taken excavator productivity and safety to another level. For instance, Caterpillar excavators come standard with two cameras, one on the right side and one at the rear. A four-camera system is also an option for contractors who want to maintain a 360° view around the excavator.
Doosan offers a standard rearview camera and an optional side view camera. Operators can view one or both (side-by-side) on the LCD screen in the operator’s cab. Doosan has also previewed its newest camera system, an all-around view monitoring system (AVM), that gives operators a 360° view of their surroundings. Five unique perspectives can be seen from the separate AVM monitor: top view, rear view, top-right view, rear-corner view, and 3D view.
Volvo Smart View was developed and has since been made standard on Volvo general-purpose excavators (EC140 and larger). Now the industry is beginning to work on a camera system that warns the operator when certain movement is detected.
Overall, these innovations have made excavator turntables more efficient and safer to use. With increased adoption of technologies like 3D grade control, remote control operation, and even certain levels of autonomous operation, the future of excavator tech looks promising.
