Thrust Bearings.

What are Thrust Bearings?

Thrust bearings, also known as axial bearings, are rotary components designed to carry load acting along the axis of a shaft rather than across it. Where a radial bearing resists force pushing sideways on the shaft, a thrust bearing handles the end-on push that a radial bearing cannot, which is what earns it a category of its own. 

A thrust ball bearing consists of two flat, washer-like races with a ring of precision balls held between them in a pressed-steel cage. One race turns with the shaft while the other sits against the housing and the balls roll in the groove between the two. The result is a compact component that lets a loaded shaft rotate freely while transferring the axial force cleanly into the surrounding structure.

How Thrust Bearings Work

A thrust bearing works by passing axial load through its rolling elements rather than through sliding metal. The balls run in a groove between the shaft washer and the housing washer, with the pressed steel cage keeping them evenly spaced so the load spreads across every ball. As the shaft turns, the balls roll rather than drag, which keeps friction low and lets the bearing carry a surprising amount of load for its size. These are single-direction thrust ball bearings, so they take load pushing one way along the shaft and are fitted with that thrust direction in mind.

Picture a motorised rotary table on a workbench, the kind used to present a workpiece to a cutting tool at set angles. The platform sits on a vertical shaft and the combined weight of the platform and the workpiece presses straight down that axis. A thrust ball bearing fitted between the rotating platform and the fixed base takes that entire downward load on its ring of balls, so the table turns smoothly under load without the shaft grinding against the base. 

For loads beyond the reach of a ball bearing, a roller thrust bearing swaps the balls for cylindrical rollers to spread force over a larger contact area, but for compact, precise, moderate-load duty the thrust ball bearing remains the practical choice.

Materials Thrust Bearings Are Made From

Two metals cover the thrust range, one chosen for load and one for corrosion resistance:

• Steel - (AISI 52100): A through-hardened chrome bearing steel with the hardness and fatigue strength to carry the full axial rating, best suited to clean, dry running.
• Stainless Steel - (420): A martensitic stainless with useful hardness and strong corrosion resistance, suited to lighter axial loads in wet or chemically exposed positions.

Sizes and Types of Thrust Bearings Available

Accu's thrust bearings span five series, from the miniature F and B ranges up to the heavier-duty 51100 and 51200 bearings, covering a wide spread of axial loads in a compact footprint.

• Inside diameters: from 2 mm to 12 mm
• Outside diameters: from 6 mm to 26 mm
• Thickness: from 3 mm to 11 mm
• Dynamic load ratings: from 123 N to 12,700 N

Every bearing is held to tight tolerances, with a thickness tolerance of +0.02 to -0.25 mm. Each is supplied in its natural finish with no additional coating or plating applied and all are single-direction thrust ball bearings running on a pressed steel cage as standard.

The five series give a clear step up in capacity as your axial load rises:

• F and B series: compact miniature thrust bearings for lighter axial duty on small vertical shafts.
• SB series: the stainless steel equivalent of the B series, for the same sizes in corrosive or washdown environments.
• 51100 and 51200 series: heavier-duty bearings carrying the highest ratings in the range, up to 12,700 N dynamic and 17,000 N static, with grease and oil speeds published separately.

Each series is offered in Steel - (AISI 52100) as standard and, where an S prefix is shown on the part number, in Stainless Steel - (420) for corrosion resistance.

FAQs

Q: What does a thrust bearing do?

A: A thrust bearing carries axial load, meaning force acting along the axis of the shaft rather than across it. It sits between a rotating part and a fixed one, letting the shaft turn freely while transferring that end-on load into the housing. 

In a thrust ball bearing, the load passes through a ring of balls running between two washer-like races, so rolling contact does the work rather than sliding metal. That makes it the natural choice for vertical shafts, turntables and gearbox layouts where weight or reaction force presses straight down the shaft axis.

Q: Can you drive with a broken thrust bearing?

A: The question usually refers to the crankshaft thrust bearing in a car's engine, which controls the crankshaft's end float. A failed thrust bearing lets the crankshaft move along its axis, which quickly damages the clutch, the main bearings and the crankshaft itself, so the vehicle should not be driven. 

The same principle holds for any machine. Once a thrust bearing fails, the shaft is free to float axially and the resulting misalignment and metal-to-metal contact spread damage through the assembly. A failed thrust bearing should always be replaced before the equipment runs again.

Q: What are the signs of thrust bearing failure?

A: The common warning signs are increased axial play or end float in the shaft, unusual noise such as grinding, rumbling or knocking under load, vibration and a rising temperature at the bearing. In rotating machinery you may also notice reduced running smoothness or visible wear debris. 

Because a thrust bearing takes its load along the shaft axis, any perceptible back-and-forth movement of the shaft is a strong symptom that the bearing is worn or failing and should be inspected. Catching these signs early stops the axial float from damaging neighbouring components.

Bespoke Thrust Bearings Manufacture.

High precision, bespoke manufacture of Thrust Bearings to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.