Comparing Internal and External Gear Slewing Bearings
Explore key differences between internal and external gear slewing bearings.
| Features | Internal Gear Slewing Bearings | External Gear Slewing Bearings |
|---|---|---|
| Gear Teeth Location | Teeth inside the inner ring | Teeth outside on the outer ring |
| Space Requirements | Fits tight spaces, saves space | Needs more room outside bearing |
| Load Capacity | Good for medium loads | Handles heavy loads better |
| Maintenance Ease | Harder to inspect and fix | Easy to check and repair |
| Protection from Contaminants | Gear teeth protected inside | Gear teeth exposed, needs care |
| Lubrication Retention | Keeps oil longer, less relubrication | Needs more frequent lubrication |
| Cost Efficiency | More costly, complex manufacturing | Cheaper for large sizes |
| Typical Applications | Small machines, dusty environments | Large machines, cranes, wind turbines |
| Transmission Efficiency | Lower stress, smoother operation | Better for slow, strong jobs |
Internal gear slewing bearings have teeth inside the ring. External gear slewing bearings have teeth outside the ring. Where the gear is placed changes how loads are handled. It also affects how bearings fit in machines. Makers pick internal or external gear slewing bearings for different reasons. They look at space, load type, and how easy it is to fix.
- External gear slewing bearings are used most around the world. They are popular because they are easy to reach and help machines move exactly.
- Internal gear slewing bearings are becoming more common now. They work well in small machines and places with little space.
Key Takeaways
- Internal gear slewing bearings have teeth inside the ring. This saves space and keeps the gear safe from dust and dirt.
- External gear slewing bearings have teeth outside the ring. They are easier to check, fix, and can hold heavy loads.
- Internal gear bearings last longer in dirty or small spaces. External gear bearings are best for big machines that need strong turning power.
- Picking the right bearing depends on machine size, load, where it is used, and how easy it is to take care of.
- Use a checklist to choose bearings carefully. Think about space, weight, protection, and how to keep them working well. This helps machines work smoothly.
Slewing Bearings: Key Difference
Gear Placement
The biggest difference is where the gear teeth are. Internal gear slewing bearings have teeth on the inside ring. External gear slewing bearings have teeth on the outside ring. This small change makes a big difference.
- Internal gear slewing bearings:
- The gear teeth are hidden inside.
- This design looks neat and tidy.
- The teeth stay safe from dust and dirt.
- External gear slewing bearings:
- The gear teeth are on the outside edge.
- This design makes the gear easy to reach.
- It is easier to check and fix the gear.
Where the gear teeth are changes how engineers pick slewing bearings. Internal gear types are good for small spaces and when protection is needed. External gear types are better for machines that need easy checks and repairs.
Performance Impact
Where the gear teeth are changes how slewing bearings work. Internal gear slewing bearings keep oil inside longer. They also keep out dust better. This means they last longer and do not wear out fast. The teeth inside the ring lower stress when moving. Machines with internal gear slewing bearings run smoother and need less fixing.
External gear slewing bearings have other good points. The teeth on the outside make it easier to make the bearing. Engineers can check the gear quickly. These bearings can use bigger gear ratios. This helps move heavy things with less force on the pinion gear. External gear slewing bearings also save space in some machines.
Note: Both types of slewing bearings are important. The best one depends on what the machine needs, where it works, and how often it needs fixing.
Internal Gear Slewing Bearing
Structure
An internal gear slewing bearing has gear teeth inside the inner ring. The outer ring is smooth and does not have teeth. The inner ring connects right to the drive part. Engineers pick this type for small machines. The gear is safe inside the bearing, so dust and dirt stay out. Balls or rollers move between the two rings. This design lets the bearing fit in small spaces where external gears cannot fit.
Advantages
Internal gear slewing bearings have many good points. The gear teeth are inside, so they stay clean and last longer. Machines with these bearings are quieter because the gear is covered. The design keeps the gear safe from rough places, so you do not need to fix it often. These bearings help keep oil inside, so they last longer. The small size saves space and works well for small machines.
Tip: Internal gear slewing bearings are great when space is tight and you need to keep out dust.
Disadvantages
Books and guides say there are some bad points too. If the load is not even, the races can bend and not last long. You must use the right oil, or the bearing can get damaged. Heavy loads make the bearing wear out faster. If the bearing turns slow, it can get small chips and pits. If the heat treatment is not done right, the bearing can break early. If there is too much play, the bearing can get loose and stop working. Tiny cracks from heat can grow and break the bearing. Engineers must make sure the bearing is set up right to stop problems.
| Disadvantage | Impact on Bearing |
|---|---|
| Uneven load distribution | Shorter working life |
| Poor lubrication | Spalling, pitting, wear |
| Heavy loads | Increased wear and tear |
| Improper heat treatment | Early failure |
| Axial play | Slackness, breakdowns |
External Gear Slewing Bearing
Structure
An external gear slewing bearing has gear teeth on the outside ring. The gear is open, so it is easy to connect to other parts. Engineers use this type for big machines. Balls or rollers sit between the rings and help hold heavy things. The outside gear can be bigger, so more teeth fit around it. This helps the bearing handle more turning force and heavier loads.
Advantages
External gear slewing bearings have many good points in factories.
- The open gear is easy to check and fix.
- A bigger gear and more teeth help move heavy things with less effort.
- These bearings spread weight well, so they last longer.
- They help machines move in a very exact way.
- The design is great for slow, strong machines like cranes and wind turbines.
- For big sizes, these bearings cost less than internal gear types.
- If one part breaks, the gear system keeps working and stays safe.
Tip: External gear slewing bearings are best for big machines that need to work well and be easy to fix.
| Performance Aspect | External Gear Slewing Bearings | Internal Gear Slewing Bearings |
|---|---|---|
| Gear Location | On outer ring, easy to connect to other parts | On inner ring, small and keeps gear safe |
| Torque & Load Capacity | Bigger gear and more teeth; handles more force and weight | Good for medium loads and smaller machines |
| Transmission Efficiency | Works better in slow, strong jobs | Not as good for strong jobs |
| Environmental Protection | Gear is open, easy to clean but needs care | Gear is covered, keeps out dirt and dust |
| Cost | Cheaper for big sizes | Costs more because it is harder to make |
| Typical Applications | Big cranes, wind turbines, heavy machines | Radar, military, and small, exact machines |
Disadvantages
External gear slewing bearings have some problems too. The open gear teeth can get dirty or wet, so you must clean them often. Engineers need to check the gear a lot to stop damage. The open design means you must add oil and protect it from bad weather. In dirty places, the gear can wear out faster. Machines with these bearings should have covers or seals to keep the gear safe.
Slewing Bearing with External Gear vs Internal Gear
Comparison Table
The table below shows how slewing bearings with external gear and internal gear are different. It talks about where the gear teeth are, how much weight they can hold, how long they last, and how well they keep out dirt.
| Aspect | Slewing Bearing with External Gear | Slewing Bearing with Internal Gear |
|---|---|---|
| Gear Teeth Location | Teeth are outside, easy to reach | Teeth are inside, hidden and safe |
| Installation & Debugging | Easy to put in and adjust | Harder to install because space is tight |
| Load Capacity | Can hold more weight, good for big machines | Best for medium weight and smaller machines |
| Service Life | Lasts a long time, but needs cleaning often | Lasts longer, teeth stay clean and wear less |
| Protection from Contaminants | Not much protection, teeth can get dirty | Better protection, teeth stay clean inside |
| Lubrication Retention | Needs oil more often | Keeps oil longer, needs less care |
| Fault Diagnosis & Inspection | Easy to check and fix | Harder to look at and find problems |
| Transmission Stress & Wear | Bigger size lowers force on pinion | Less stress, less wear |
| Space Requirements | Needs more room outside the bearing | Saves space, fits in small places |
| Typical Applications | Used in cranes, wind turbines, big machines | Used in radar, military, medical, and small machines |
Note: Both types can have hard gear surfaces to make them stronger and last longer. The best one depends on what the machine needs, how much space there is, and how much weight it must hold.
Quick Reference
When picking between slewing bearing with external gear and internal gear, engineers think about a few things:
- Internal gear slewing bearings have teeth on the inside ring. This is good when there is not much space outside the bearing.
- Slewing bearing with external gear has teeth on the outside ring. This type is better for machines that lift heavy things.
- Both types can work with other gears, and the gear fit can be changed for each job.
- Internal gear types keep out dust better and hold oil longer, so you do not need to fix them as much.
- Slewing bearing with external gear is easier to put in, check, and fix.
- External tooth slewing bearing uses a bigger size. This helps lower the force and turning power needed on the pinion gear.
- Engineers pick the right type by thinking about size, weight, and how easy it is to take care of the bearing.
Tip: If a machine works in a dirty or dusty place, internal gear types protect better. For heavy jobs or when you need to reach the gear easily, slewing bearing with external gear is usually best.
Applications
Internal Gear Applications
Internal gear slewing bearings are used when space is small and dust is a problem. These bearings hold medium weights and help things turn smoothly. Engineers pick them for machines that must work well in tough places.
| Industry | Typical Applications |
|---|---|
| Heavy Machinery | Tower cranes, excavators, earthmovers |
| Aerospace & Defense | Radar systems, missile launchers, satellite tracking |
| Renewable Energy | Solar tracking systems, wind turbines |
| Robotics | Precision motion control, automated arms |
| Marine & Offshore | Heavy load rotation, positioning systems |
Radar and military machines use internal gear slewing bearings because they are small and safe. Robots and automation systems use them to move exactly. In renewable energy, these bearings help solar panels and wind turbines follow the sun or wind. The covered gear keeps out dirt and helps the bearing last longer.
Tip: Internal gear slewing bearings are best for small spaces and dirty places.
External Gear Applications
External gear slewing bearings are used when machines need strong turning power and easy fixing. These bearings can hold heavy things and are simple to check and repair. The open gear design is good for big machines and outdoor tools.
| Industry / Machine | Role of External Gear Slewing Bearings |
|---|---|
| Wind Turbines | Support hub, transmit loads, enable rotation |
| Harbour Cranes | Stable lifting, power transfer |
| Excavators | Boom, stick, bucket movement, cab rotation |
| Aerial Work Platforms | Rotational movement, load handling |
| Packing Machines | Precise rotational motion |
| Medical Equipment | Durable, accurate rotation |
| Forestry and Farming | Heavy load handling, rotation |
| Water Treatment Equipment | Rotational parts, durability |
| Filling Machines | Precise rotation for filling |
| Mining Machinery | Heavy load rotation, power transfer |
| Precision Robots | Accurate, durable movement |
Big building machines and wind turbines use external gear slewing bearings for strong turning and heavy loads. These machines need regular care, and the open gear makes this easy. Medical and packing machines also use these bearings for exact turning.
Note: Engineers look at space, weight, and the work area before picking a type. Internal gear slewing bearings protect better and are smaller. External gear slewing bearings give more turning power and are easier to fix.
Choosing the Right Slewing Bearing
Selection Checklist
Picking the right slewing bearing helps machines work well and last longer. Engineers use a checklist to make sure the bearing is a good fit. Here are the main steps:
- Look at where the machine works. Check if it is hot, cold, wet, or dusty.
- Think about how easy it is to get new bearings. Make sure it is simple to check and fix them.
- Find out how much weight the bearing will hold. See if it needs to handle side or up-and-down loads.
- Choose the bearing type for the weight. Ball bearings are for lighter jobs. Roller bearings are for heavier jobs.
- If the machine has both side and up-and-down loads, pick the right kind. You might need deep groove ball bearings, angular contact ball bearings, or tapered roller bearings.
- Check the space for the bearing. Make sure it fits the shaft or the part it goes into.
- Make sure the bearing size is right. The hole, width, and outside must match the machine.
- Use charts to compare different bearings. Pick the one that works best for the machine.
- Think about how fast the machine goes and if it gets hot. Fast or hot machines need special bearings.
- Pick bearings with good seals or special covers to keep them safe for a long time.
- Choose the right grease or oil. It should work with the machine’s heat and be easy to use.
- Make sure the bearing is not too tight or too loose inside. This helps stop noise, shaking, or breaking.
- Check how much weight the bearing can really hold. It must be strong enough for the job.
- Make sure the bearing is made from good materials and is treated right. Good materials help it last longer.
- Make sure the seals and oiling ways are right for where the machine works.
Tip: If you pick the wrong bearing, it can break early. Always check every step on the list.
Decision Factors
Engineers look at many things when picking between internal gear and external gear slewing bearings. Each thing changes how well the bearing works in the machine.
| Decision Factor | Internal Gear Slewing Bearing | External Gear Slewing Bearing |
|---|---|---|
| Load Capacity | Good for medium loads | Best for heavy loads |
| Space Constraints | Fits tight spaces | Needs more room outside the bearing |
| Environmental Protection | Keeps out dust and dirt | Needs extra care in dirty places |
| Maintenance | Less frequent, harder to inspect | Easier to check and repair |
| Installation | More complex, needs careful alignment | Easier and faster to install |
| Service Life | Longer in harsh environments | Long, but needs regular cleaning |
| Lubrication | Holds oil longer, less frequent relubrication | Needs more frequent lubrication |
| Application Fit | Best for small, protected machines | Best for large, heavy-duty machines |
When making the final choice, engineers think about:
- What the machine needs, like weight, speed, and how exact it must be.
- Where the machine works, such as how hot, wet, or dirty it is.
- The size and shape of the machine.
- How often the bearing will need fixing.
- If the bearing needs special materials or coatings to stop rust or wear.
- If the bearing company gives good help and support, like TFL.
Note: The best slewing bearing depends on the job. Internal gear types are better for dirty places and save space. External gear types are stronger and easier to fix. Always pick the bearing that matches what the machine really needs.
Slewing bearings with internal gears are small and fit tight spaces. They keep out dust well and help machines turn smoothly. External gear types are easier to fix and can hold heavy things. They work best in big machines. Picking the right type depends on space, weight, and where the machine works.
| Decision Point | Internal Gear | External Gear |
|---|---|---|
| Space Saving | ✔️ | |
| Easy Maintenance | ✔️ | |
| Protection | ✔️ | |
| Heavy Loads | ✔️ |
If you need help or special answers, you can talk to TFL Bearings on their website, by email, or on social media.
FAQ
What is the main difference between internal gear and external gear slewing bearings?
Internal gear slewing bearings have teeth on the inside ring. External gear slewing bearings have teeth on the outside ring. This changes how each bearing fits in machines. It also changes how well each one handles weight.
Which type offers better protection against dust and dirt?
Internal gear slewing bearings protect better from dust and dirt. The teeth are inside the ring, so dirt cannot get in easily. External gear slewing bearings have teeth outside, so they get dirty faster. They need more cleaning and care.
Which slewing bearing is easier to inspect and maintain?
External gear slewing bearings are easier to check and fix. The teeth are outside, so you can see and reach them quickly. Internal gear slewing bearings are harder to check because the teeth are inside.
When should engineers choose internal gear slewing bearings?
Engineers pick internal gear slewing bearings when space is small. They also use them when it is important to keep out dirt. These bearings work well in places with lots of dust or dirt.
What applications suit external gear slewing bearings best?
External gear slewing bearings are good for big, heavy machines. They work well in cranes and wind turbines. These bearings can hold a lot of weight and are easy to fix. Their design helps machines move strong and exactly in factories.
