Name: axial load support in pivot bearings
Uploaded: 2025-05-22T09:06:04.000Z
Duration: 1 min 23 s
Channel: JoVE

轴承是一种机械元件，可允许两个部件之间产生相对运动，同时减少机械装置中的摩擦和磨损。
它还有助于分散载荷，这些载荷可能是径向的、轴向的，或两者兼有。
枢轴轴承可承受旋转轴上的轴向载荷。其支撑面可以是平面、圆锥面或截锥面。
考虑一个承受轴向载荷的平面止推轴承，其总承压面积为 πR2。
轴承上的均匀压力表示为载荷与轴承面积之比。
接下来，考虑在支承区域内一个半径为 r、厚度为 dr 的无穷小环；可估算传递到该环上的载荷。
此时，阻碍圆环滑动的摩擦力在半径 r 处沿切线方向作用。
因此，通过计算圆环的力矩并在径向范围内进行积分，可以估算出克服摩擦力所需的轴的力矩。

<ol>
	<li>希伯勒，RC（2016 年）。工程力学 \u2012 静力学和动力学。新泽西州霍博肯:Pearson Prentice Hall。第 447 页。</li>
</ol>

枢轴轴承

Pivot Bearings

在机械系统中，轴承对于促进两个组件之间的相对运动并减少摩擦和磨损至关重要。它们帮助分配不同类型的负荷（径向、轴向或两者的组合）到机械部件上，确保其能够平稳高效的运行。 枢轴轴承是一种专门设计用于支撑旋转轴上轴向负荷的轴承。枢轴的表面或轴心位于轴的末端，并用来支撑轴向推力。根据应用的不同，枢轴可能具有平坦、圆锥或截平面等不同的表面。 在平坦枢轴轴承中，当受到轴向负荷时，施加在轴承上的平均压力可以通过负荷与轴承面积的比例来进行计算。这种压力的分布有助于减少轴承表面的摩擦和磨损，从而提高其运行效率和使用寿命。 为了进一步分析作用在平坦枢轴轴承上的力，我们可以对轴承面积内的一个无穷小环进行分析，它具有半径r和厚度dr。通过压力分布可以得出传递给这个环的负荷。 当轴发生旋转时，摩擦力会阻止环的滑动，并且在半径r处产生切向方向的力。通过计算环的力矩，并且在限制半径的区域内来对其进行积分，可以确定轴的力矩如下： <img alt="Equation 1" src="/files/ftp_upload/14324/14324_Equation_1v2.svg" style="text-align: center; height: 28px;"> 该计算为在不同负载条件下轴承的性能和效率提供了有宝贵的见解。 由于枢轴轴承在旋转轴上有着支撑轴向负荷的独特能力，它们被广泛应用于各种行业和机械系统中。这些多功能组件可以在涡轮机、发电机、泵和汽车组件（如转向系统和传动组件）等旋转机械中找到。此外，枢轴轴承（包括起落架和飞行控制面）还在航空航天应用中起着关键作用。工业设备（如起重机、绞车和输送机）也依赖于枢轴轴承以实现其高效的操作和可靠的性能。因此，枢轴轴承在各个行业的广泛应用中凸显了它们在维持平稳有效的机械系统方面的重要性。

在机械系统中，轴承对于促进两个部件之间的相对运动至关重要，同时可最大限度地减少摩擦和磨损。它们有助于……

Education

教育

JoVE Core

Mechanical Engineering

机械工程

Unit 1

第一单元

Friction

摩擦

KEY TERMS AND CONCEPTS

关键术语与概念

axial load support in pivot bearings

Pivot bearings support axial loads on a rotating shaft. A bearing helps two parts move relative to each other while reducing friction and wear. In this design, the pivot is placed at the end of the shaft to carry the axial thrust.

The pivot surface can be flat, conical, or truncated, depending on the application. In a flat pivot bearing, the axial load is spread over the bearing area. The pressure is uniform and can be found by dividing the load by the area.

To study the forces more closely, engineers can look at a tiny ring inside the bearing surface. This ring has a radius r and a small thickness dr. The load on the ring depends on the pressure across the bearing area.

As the shaft turns, friction acts on the ring and resists sliding. This force acts tangentially at radius r. By finding the moment of the ring and integrating across the radial limits, the moment of the shaft can be determined. This helps explain how the bearing performs under different load conditions.

Pivot bearings are used in many machines and industries. They appear in turbines, generators, pumps, steering systems, and transmission assemblies. They are also important in aerospace parts such as landing gear and flight control surfaces, as well as in cranes, winches, and conveyors.

Axial Load Support in Pivot Bearings

dry friction

Dry Friction in Crates and Everyday Motion

Dry friction appears when two solid surfaces touch and try to move past each other. Students can see it when they walk, slide a box across a table, or rub their hands together. Even though it is common, the forces behind it are not easy to see. A simple crate on a rough horizontal floor helps explain the idea. When an external force pushes the crate sideways, two main forces act on it. The normal force acts perpendicular to the surface and helps balance the crate’s weight, while the frictional...

static friction

Static Friction at the Point of Slip

Static friction is the force that keeps two surfaces from starting to slide past each other. It acts when there is a tendency for motion, but not yet actual slipping. This force helps explain everyday actions like walking on the ground and driving a car. A towing example shows how static friction changes as force is applied. A truck pulls a car with a rope, and the car stays still at first. The car is in static equilibrium, which means the forces on it are balanced. Gravity and the normal...

kinetic friction

Sliding Friction Between Moving Surfaces

Kinetic friction is the sliding friction that acts when two surfaces move against each other. It opposes relative motion and acts parallel to the contact surface, in the opposite direction of travel. In the truck and car example, the car first stays still because static friction holds it in place. When the truck’s force becomes greater than the limiting static frictional force, the friction at the contact surface drops to a lower value. The car then begins to slide, and its speed increases. At...

characteristics of dry friction

Static and Kinetic Dry Friction

Dry friction is the resistance between two solid surfaces that move against each other without lubrication or any fluid. A common example is a gardener pushing a wheelbarrow across the ground. The wheel and the ground create dry friction that slows the motion. Before the wheelbarrow starts to move, static friction acts at the contact surface. Static friction is the force that opposes motion before slipping begins, and it helps keep the wheelbarrow stable. It is present only when there is no...

types of friction problems

Dry Friction in Crate, Ladder, and Frame Problems

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friction: problem solving

Friction on a Banked Road

Friction on a banked road affects whether a bus stays steady while it moves at constant speed. In this problem, a bus with a mass of three megagrams travels on a sloped road. The coefficient of static friction between the tires and the road is 0.5. The goal is to find the maximum bank angle where the bus will not slip or tip. To solve the motion part, the forces on the bus must be shown first. These include gravity, the normal force, and friction. The normal force is the push from the road,...

wedges

Wedges and Self-Locking Stability

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frictional forces on screws

Square-Thread Screw Mechanics and Friction

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upward impending motion

Screw Jack Force and Friction Analysis

A square-threaded screw jack lifts heavy loads by turning handle force into a twisting moment. Its upward motion depends on overcoming static friction between the screw threads and the jack. To study this motion, the thread can be treated as if it were a block on the groove of the jack after the thread is completely unraveled. A free-body diagram helps show the forces acting on this simplified system. The force at the handle creates a horizontal force that pushes the movable thread up the...

self-locking screw

Screw Jack Self-Locking Behavior

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screw: problem solving

Screw Torque and Self-Locking

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frictional forces on flat belts

Flat Belt Tension and Friction

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flat belts: problem solving

Flat Belt Forces and Pulley Moment

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pivot bearings

Pivot bearings support axial loads on a rotating shaft. A bearing helps two parts move relative to each other while reducing friction and wear. In this design, the pivot is placed at the end of the shaft to carry the axial thrust. The pivot surface can be flat, conical, or truncated, depending on the application. In a flat pivot bearing, the axial load is spread over the bearing area. The pressure is uniform and can be found by dividing the load by the area. To study the forces more closely,...

collar bearings

Friction Torque in Collar Bearings

Collar bearings support axial loads on rotating shafts, and their friction helps determine the torque needed to start motion. They are used in many machines and may have a single collar or multiple collars, depending on the application and load needs. For a single collar bearing under an axial load, the contact area is the ring-shaped region between the external radius and the internal radius of the collar. If the bearing is assumed to support the load evenly, the uniform normal pressure is...

journal bearings

Friction Moment in Journal Bearings

Journal bearings support rotating shafts and axles while helping keep them stable. They are used in machines such as engines, turbines, and pumps. Their job is to reduce friction, wear, and vibration. A journal bearing works by keeping a thin film of lubricant between the bearing surface and the rotating shaft. This film limits direct contact and lowers frictional force. The video uses a rope winch with dry or only partly lubricated journal bearings to show the idea. As the spool turns...

bearings: problem solving

Double-Collar Bearing Torque Calculations

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rolling resistance

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rolling resistance: problem solving

Lawn Roller Force Calculation

Rolling resistance is the force that makes a rolling object harder to move across a surface. It is also called rolling friction. It comes from deformation in the object and the surface that touch each other. Internal friction, hysteresis, and other energy losses in the materials also play a role. Because of this force, extra energy is needed to keep a wheel, tire, or ball moving. The video applies this idea to a lawn roller. The roller has a mass of 100 kg, a radius of 25 cm, and a coefficient...

key terms and concepts

Learn how pivot bearings support axial loads on rotating shafts, reduce friction, and appear in turbines, generators, pumps, cars, aircraft, and industrial equipment.

Axial Load Support in Pivot Bearings | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Axial Load Support in Pivot Bearings

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