China factory Needle Roller Bearing with Inner Ring Na4902 Open 15X28X13 mm for Skew Bevel Helical Gearbox/ Worm Reduction Gearboxes/ Planetary Gearbox with Good quality

Merchandise Description

The needle bearing NA4902 has slim cylinders as rolling factors and can take up high radial forces with its massive bearing rings. It is suited for space-preserving set up.



  • appropriate for high radial loads
  • require a tiny radial assembly area
  • situation for the use is a hardened and ground shaft
  • with an annular groove and lubrication holes in the outer ring
  • permits axial displacements – dependent on the width of the raceway on the shaft
  • material: chrome metal (Cr15)
  • temperature resistance: from circa -20 °C up to +one hundred twenty °C

Application Area:


Needle roller bearing types: can be divided into 2 buildings with internal ring (NA) and with out interior ring (RNA). 


one. Needle roller bearings with stamped outer rings. There are 2 sorts: perforated and sealed. Scope of application: Stamped outer ring needle roller shafts with cages are mostly employed in gearboxes of equipment tools, vehicles, and motorcycles or textile equipment. The stamped ferrule needle roller bearings with no cage are employed in the frame of the plane and the shaft end of the primary CZPT of the missile.


two. Entity ferrule needle roller bearings Scope of software: mostly utilised in equipment instruments and automobile gearboxes. 


three. Roller needle roller bearings Scope of application: printing machinery, pasture equipment, agricultural machinery, rollers for CZPT rails of CNC equipment, conveyor lines, etc. 


4. Needle roller and cage assembly. Scope of software: mainly utilised for huge and little ends of connecting rods of gearboxes, motorcycles and automobiles


Good quality items make operate easier.


ZheJiang CZPT Bearing can provide you with the broadest achievable array of bearings. In addition to Ball bearing, Roller bearing, Needle bearing, Pillow Blocks, we manufacture Flange blocks, Rolling mill bearing, Slide bearing and Water pump bearing. Our unparalleled encounter as a total producer and exporter for these industries is crucial for the growth and application of a premier product line for all common industries.

We pleasure ourselves on our capability to provide every single buyer, from yard mechanics, to independent shop proprietors, to automotive technicians, to large manufacturing plants. Our Target Industries served are Agricultural Tools, Cranes, Electric powered Motors, Gearboxes, Content Dealing with, Packaging Equipment, Power Tools, Pumps, Railways and Transportation, Robotics, and items for Textile Machinery. ZheJiang Bearing Firm is a more robust and increasing exporter of bearing in China.

In addition to production commodity-dependent bearing items, CZPT Bearing helps make custom bearing options for OEM. ZheJiang CZPT bearing has stringent high quality manage standards and maintains comprehensive manage more than offer, using only the highest quality bearing metal.

Our mission is to completely provide for you. Well into our much more than 10 many years of company, we are assured that you may uncover what you’re looking for in bearing product listed here. Make sure you call, electronic mail, or stop by for a lot more details.

We are extremely self-confident in our merchandise, and we are certain that we can earn your trust!



Q: Is your business a manufacturing unit or a trading organization?
A: We have our possess manufacturing facility, our sort is manufacturing facility & trade.

Q: What is your firm’s least purchase quantity?
A: 1pc.

Q: Could you tell me the content of your bearing?
A: We can offer you with chrome metal, stainless metal, ceramic and carbon metal.

Q: Can you affix my brand name (logo) on these items?
A: Of course, we can customize it for you according to samples or drawings.

Q: Could you offer samples for free of charge?
A: Of course, We are honored to provide you samples for good quality verify, do you only want to spend for the freight?

Q: Could you offer door to doorway service?
A: Of course.

Q: How prolonged do I need to have to wait ahead of my merchandise arrive?
A: Worldwide express shipping takes 3-5days, 5-7 days for air transportation and 35-40 times for sea transportation.

Q: What payment techniques do you settle for?
A: T/T, L/C.

How to Decide on:
– Choose the bearing model or measurement.
–  Pricing adjusts according to the bearing dimensions picked.

For Further Data About Our Merchandise or Providers, Please Contact Our Sales Group by way of Mobile phone or Email These days.


Worm Shafts and Gearboxes

If you have a gearbox, you may possibly be asking yourself what the greatest Worm Shaft is for your software. There are many factors to take into account, including the Concave form, Number of threads, and Lubrication. This report will describe every factor and support you choose the proper Worm Shaft for your gearbox. There are many choices accessible on the market place, so will not hesitate to shop all around. If you are new to the planet of gearboxes, read through on to find out far more about this popular sort of gearbox.
worm shaft

Concave form

The geometry of a worm gear may differ substantially dependent on its maker and its supposed use. Early worms had a fundamental profile that resembled a screw thread and could be chased on a lathe. Later, tools with a straight sided g-angle had been developed to create threads that have been parallel to the worm’s axis. Grinding was also produced to increase the end of worm threads and lessen distortions that take place with hardening.
To decide on a worm with the correct geometry, the diameter of the worm gear should be in the identical unit as the worm’s shaft. After the basic profile of the worm gear is established, the worm gear tooth can be specified. The calculation also requires an angle for the worm shaft to avoid it from overheating. The angle of the worm shaft need to be as close to the vertical axis as attainable.
Double-enveloping worm gears, on the other hand, do not have a throat around the worm. They are helical gears with a straight worm shaft. Since the tooth of the worm are in speak to with each and every other, they make considerable friction. In contrast to double-enveloping worm gears, non-throated worm gears are much more compact and can handle smaller masses. They are also easy to manufacture.
The worm gears of different manufacturers provide numerous rewards. For occasion, worm gears are one particular of the most successful methods to increase torque, while reduce-high quality components like bronze are difficult to lubricate. Worm gears also have a minimal failure fee since they enable for substantial leeway in the design procedure. In spite of the differences among the two standards, the all round performance of a worm gear program is the very same.
The cone-formed worm is one more type. This is a technological plan that brings together a straight worm shaft with a concave arc. The concave arc is also a beneficial utility product. Worms with this condition have a lot more than three contacts at the exact same time, which signifies they can decrease a large diameter with no excessive wear. It is also a relatively lower-price model.
worm shaft

Thread pattern

A good worm equipment needs a ideal thread sample. There are a few important parameters that decide how good a thread pattern is. Firstly, the threading pattern must be ACME-threaded. If this is not attainable, the thread should be made with straight sides. Then, the linear pitch of the “worm” need to be the exact same as the circular pitch of the corresponding worm wheel. In straightforward terms, this means the pitch of the “worm” is the very same as the circular pitch of the worm wheel. A quick-change gearbox is typically utilised with this variety of worm gear. Alternatively, direct-screw adjust gears are utilized as an alternative of a swift-alter equipment box. The pitch of a worm gear equals the helix angle of a screw.
A worm gear’s axial pitch have to match the round pitch of a gear with a greater axial pitch. The round pitch is the length between the points of enamel on the worm, although the axial pitch is the distance between the worm’s tooth. Yet another factor is the worm’s direct angle. The angle in between the pitch cylinder and worm shaft is known as its lead angle, and the higher the guide angle, the better the effectiveness of a gear.
Worm gear tooth geometry may differ relying on the maker and intended use. In early worms, threading resembled the thread on a screw, and was simply chased utilizing a lathe. Afterwards, grinding enhanced worm thread finishes and minimized distortions from hardening. As a end result, these days, most worm gears have a thread sample corresponding to their size. When choosing a worm gear, make positive to check out for the number of threads before purchasing it.
A worm gear’s threading is essential in its operation. Worm tooth are usually cylindrical, and are organized in a sample related to screw or nut threads. Worm enamel are usually formed on an axis of perpendicular in contrast to their parallel counterparts. Due to the fact of this, they have greater torque than their spur equipment counterparts. Furthermore, the gearing has a minimal output pace and large torque.

Variety of threads

Distinct kinds of worm gears use different quantities of threads on their planetary gears. A one threaded worm gear ought to not be utilized with a double-threaded worm. A solitary-threaded worm gear need to be employed with a one-threaded worm. Solitary-threaded worms are much more effective for speed reduction than double-threaded ones.
The amount of threads on a worm’s shaft is a ratio that compares the pitch diameter and variety of tooth. In general, worms have 1,2,4 threads, but some have a few, five, or 6. Counting thread commences can support you decide the amount of threads on a worm. A single-threaded worm has fewer threads than a numerous-threaded worm, but a multi-threaded worm will have a lot more threads than a mono-threaded planetary equipment.
To evaluate the variety of threads on a worm shaft, a small fixture with two ground faces is employed. The worm should be removed from its housing so that the concluded thread region can be inspected. Following figuring out the variety of threads, basic measurements of the worm’s outdoors diameter and thread depth are taken. When the worm has been accounted for, a forged of the tooth area is manufactured utilizing epoxy substance. The casting is moulded between the two tooth flanks. The V-block fixture rests from the outside diameter of the worm.
The circular pitch of a worm and its axial pitch must match the circular pitch of a larger gear. The axial pitch of a worm is the distance in between the points of the tooth on a worm’s pitch diameter. The lead of a thread is the distance a thread travels in one revolution. The direct angle is the tangent to the helix of a thread on a cylinder.
The worm gear’s pace transmission ratio is based mostly on the amount of threads. A worm gear with a high ratio can be simply reduced in a single stage by employing a established of worm gears. Even so, a multi-thread worm will have more than two threads. The worm equipment is also a lot more efficient than solitary-threaded gears. And a worm equipment with a substantial ratio will allow the motor to be employed in a selection of purposes.
worm shaft


The lubrication of a worm equipment is notably demanding, thanks to its friction and substantial sliding get in touch with power. Luckily, there are numerous options for lubricants, such as compounded oils. Compounded oils are mineral-based lubricants formulated with ten per cent or much more fatty acid, rust and oxidation inhibitors, and other additives. This mix final results in improved lubricity, decreased friction, and reduce sliding put on.
When deciding on a lubricant for a worm shaft, make sure the product’s viscosity is proper for the type of gearing used. A reduced viscosity will make the gearbox difficult to actuate and rotate. Worm gears also go through a greater sliding motion than rolling movement, so grease need to be able to migrate evenly through the gearbox. Recurring sliding motions will drive the grease away from the get in touch with zone.
One more thing to consider is the backlash of the gears. Worm gears have large equipment ratios, often three hundred:1. This is important for power apps, but is at the same time inefficient. Worm gears can produce warmth in the course of the sliding motion, so a high-top quality lubricant is important. This sort of lubricant will lessen heat and make certain best functionality. The following tips will aid you pick the right lubricant for your worm equipment.
In minimal-velocity apps, a grease lubricant may be ample. In greater-pace purposes, it’s greatest to implement a artificial lubricant to avoid premature failure and tooth dress in. In equally circumstances, lubricant decision depends on the tangential and rotational speed. It is crucial to follow manufacturer’s recommendations concerning the decision of lubricant. But remember that lubricant selection is not an effortless task.

China factory Needle Roller Bearing with Inner Ring Na4902 Open 15X28X13 mm for Skew Bevel Helical Gearbox/ Worm Reduction Gearboxes/ Planetary Gearbox     with Good qualityChina factory Needle Roller Bearing with Inner Ring Na4902 Open 15X28X13 mm for Skew Bevel Helical Gearbox/ Worm Reduction Gearboxes/ Planetary Gearbox     with Good quality