Description

XTA and XTB End Bearings for the Two Ends of a Screw Conveyor

The inlet and outlet ends of a screw conveyor use different shaft-support arrangements. The two screw conveyor end bearing assemblies may correspond to the same conveyor diameter, but they are not interchangeable.

• XTA is installed at the conveyor outlet end.
• XTB is installed at the conveyor inlet end.

XTA uses a compact sealed-bearing arrangement. XTB has a longer shaft-support structure with separate radial and axial bearing positions, defined grease quantities and a different overall installation length.

Selecting the correct assembly requires more than matching the blue mounting flange or nominal conveyor diameter. The installation end, DIN 5482 connection, shaft dimensions, mounting pattern and bearing arrangement must all correspond with the conveyor.

Match the Conveyor Diameter to Both End-Bearing Models

This table identifies the two assemblies used within the same conveyor size group. It does not mean their shafts, splines or internal bearings are identical.

The difference is especially important in the 114–139 mm range:

• XTA00ES0A uses a 28 × 35 DIN 5482 connection.
• XTB25ES0B uses a 28 × 25 DIN 5482 connection.

The model and installation end should therefore be confirmed before measurements from one assembly are applied to the other.

Why XTA and XTB Are Not Interchangeable

Their similar flange-mounted appearance can make XTA and XTB look like two versions of the same component. Internally, however, they handle different end positions and use different shaft-support arrangements.

For a 219 mm conveyor, for example:

• XTA00ES3A is the compact outlet-end assembly.
• XTB35ES3B is the longer inlet-end assembly with separate radial and axial bearings.

The installation position must be identified before choosing the model.

XTA Outlet End Bearing Specifications

XTA supports the screw shaft at the conveyor outlet through a compact bearing assembly.

Models for 168–323 mm conveyors use a 40 × 36 DIN 5482 connection. The smaller XTA00ES0A uses a 28 × 35 connection.

Dimensions: mm

The bearing number alone does not identify the complete XTA model.

XTA00ES1A through XTA00ES5A all use a 6008-2RS bearing, but their mounting-flange dimensions and corresponding conveyor diameters differ. Ordering only by the internal bearing number can therefore result in the wrong complete assembly.

XTB Inlet End Bearing Specifications

XTB combines the inlet-end shaft connection with separate radial and axial bearing positions.

The 114–139 mm model uses a 25 mm shaft and 28 × 25 spline. Models for 168–323 mm conveyors use a 35 mm shaft and 40 × 36 spline.

Dimensions: mm

The radial and axial bearings serve different positions within the XTB assembly. Both should be considered when the inlet end shows excessive movement, noise or internal wear.

Replacing only the radial bearing may not correct axial movement if the thrust-bearing position, shaft shoulder or retaining components are also worn.

A Matching Mounting Flange Is Only One Part of the Fit

An end bearing may align with the conveyor mounting flange and still be unsuitable for the internal screw shaft.

Three areas must be checked separately.

Mounting-Flange Connection

Confirm:

• Flange outside diameter
• Centre opening
• Number of mounting positions
• Thread or fastener size
• Bolt-circle diameter
• Flange thickness
• Bearing centre relative to the conveyor tube

Shaft and Spline Connection

Confirm:

• Shaft diameter
• DIN 5482 spline dimensions
• Tooth condition
• Engagement length
• Distance from the mounting flange to the shaft end
• Connection to the internal screw shaft or coupling

Installed Position

Confirm:

• Inlet or outlet end
• Overall assembly length
• Grease-fitting position on XTB
• Space around nearby supports and guards
• Access for removal and lubrication
• Alignment with the conveyor centreline

A replacement may bolt onto the mounting flange but fail to connect because its spline is different, the engagement position is too short or long, or the shaft centre does not align with the internal screw assembly.

The mounting bolts should secure an aligned bearing. They should not be used to pull the shaft sideways into the housing.

Repair the Internal Bearings or Replace the Complete Assembly?

Replacing only the internal bearing can be practical when the remaining parts are still suitable for reuse.

Internal Bearing Repair May Be Suitable When

• The housing is not cracked or distorted
• Bearing seats remain tight and undamaged
• The shaft and spline remain usable
• Mounting surfaces remain flat
• Retaining surfaces are intact
• The XTB grease passage remains clear
• The correct internal bearing arrangement can be restored

A Complete Assembly Is Usually Safer When

• The housing is cracked or deformed
• Bearing seats have become loose or oversized
• The shaft or spline is badly worn
• The mounting flange has been modified
• The grease fitting or internal passage is damaged
• Several internal components require replacement
• The original assembly order cannot be confirmed

For XTB, the radial and axial bearings should be inspected together. Replacing only the component showing the most visible damage may leave movement elsewhere in the inlet-end support.

The connected screw shaft and coupling should also be checked. A new end bearing cannot correct a bent shaft, worn spline or conveyor body that has moved away from its original centreline.

Record These Details Before Removing the Old Assembly

When the model marking is readable, photograph it before cleaning, dismantling or repainting the component.

Also record:

• Inlet or outlet installation end
• Complete XTA or XTB model
• Screw conveyor diameter
• DIN 5482 spline
• Shaft diameter on XTB
• Overall installed length
• Mounting-flange dimensions
• Bolt-hole or thread arrangement
• Distance from flange face to shaft end
• Grease-fitting position
• Orientation relative to the conveyor

Useful photographs include:

• Complete installed bearing
• Side profile
• Mounting flange
• Shaft or spline end
• Model marking
• Grease point on XTB
• Surrounding conveyor supports
• Connection to the internal screw shaft

Measurements taken before removal preserve the original installation position. Once spacers, retainers and shaft connections have been dismantled, reconstructing the previous arrangement may become more difficult.

Frequently Asked Questions

The old assembly has already been removed. How can we tell whether it is XTA or XTB?

Start with the housing structure.

XTA is normally the shorter outlet-end assembly and uses a compact sealed bearing. XTB is longer, includes a shaft section, normally has a grease point and contains separate radial and axial bearing positions.

Photos of the original installation end are still valuable. Without them, compare the overall length, shaft dimensions, bearing arrangement and model markings rather than relying only on the mounting-flange shape.

We only know that the old bearing is 6008-2RS. Can that identify the correct XTA model?

No.

XTA00ES1A, XTA00ES2A, XTA00ES3A, XTA00ES4A and XTA00ES5A all use a 6008-2RS bearing. They correspond to different conveyor diameters and mounting-flange dimensions.

The complete XTA model or the conveyor diameter and mounting dimensions are still required.

Only the outlet end is damaged. Do we need to replace both end-bearing assemblies?

Not automatically.

XTA and XTB are separate assemblies with different internal structures. The undamaged end may remain in service if it rotates smoothly, remains correctly aligned and has no excessive radial or axial clearance.

Both ends should still be inspected because movement at one end can increase the load carried by the other.

Can we rebuild the original XTB using new radial and axial bearings?

Yes, when the housing, bearing seats, shaft, retaining surfaces and grease passage remain suitable for reuse.

Use the radial and axial bearing numbers specified for the exact XTB model. Do not assume that every XTB35 assembly uses the same bearing pair: XTB35ES1B and XTB35ES2B differ from the larger ES3B, ES4B and ES5B models.

The replacement matches the mounting flange, but the shaft will not fully engage. What should we check?

Check the DIN 5482 spline, shaft diameter, tooth profile, engagement length and distance from the mounting-flange face to the shaft connection.

A matching mounting pattern confirms only the external installation. It does not confirm that the internal shaft connection is correct.

Do not force engagement by tightening the flange bolts.

The model marking is unreadable. What should we record before dismantling the conveyor?

Photograph the installed bearing from the side and from the shaft end. Record whether it is at the inlet or outlet, then measure the conveyor diameter, overall bearing length, mounting flange, bolt pattern, shaft diameter and spline connection.

On XTB, also record the grease-fitting position and any visible shaft-retaining components. These details are easier to identify before the original arrangement is taken apart.