Fluid clutches and brakes may be divided into two groups: those containing a fluid only and those containing a mixture of fluids and solids. Those containing only a fluid rely primarily upon the mass of the fluid and secondarily upon its viscosity to transmit torque. Units containing both a fluid and a solid in a particulate form rely upon the suspended solids to provide the major bond between the components that either transmit or resist torque when under the influence of an external electromagnetic field. The advantage of fluid clutches and brakes is that there is no lining to wear...

These are special-purpose clutches that are used in automatic transmissions, in devices for bringing high-speed machinery up to speed, in chain saws, in conveyor drives, and in similar industrial, vehicular, and large- and smallequipment applications. The centrifugal clutches provide a speed-dependent torque which acts only when the rotational speed exceeds a particular value; the one-way, or overrunning, clutches provide a torque that is not speed dependent once they are engaged, but is dependent on the direction of rotation; and the detent clutches provide a torque that cannot exceed a prescribed value. ...

Brake and clutch design or selection from a manufacturer’s catalog both require that we design or select a brake or clutch which has the torque capability necessary to stop or start either a machine or a mechanical component in a specified amount of time and also has the ability to dissipate the heat generated. Torque capability depends, as we have found, on the particular brake or clutch design. The heat to be dissipated does not; it depends only on the machinery being stopped and is, therefore, independent of the brake or clutch used. In this chapter we are concerned with...

All three of these brake or clutch types have no wearing parts because the torque is developed from electromagnetic reactions rather than mechanical friction. Electronic controls and a rectifier to provide direct current are required, however, for their operation. They are, nevertheless, not usually referred to as electric brakes because that term had been reserved earlier to denote friction brakes which are electromagnetically activated: those in which an electric current through a coil induces a magnetic field that engages a shoe and drum, as pictured in Chapter 4. ...

These brakes have the advantage of greater torque for a smaller axial force than either type of disk brake discussed in Chapter 5. The magnitude of the improvement is limited, however, by the observation that for small cone angles a disengagement force may be required, depending on the friction coefficient, because the inner and outer cones may tend to wedge together. This is because on engagement the inner cone is radially compressed and the outer cone is radially enlarged as the brake is engaged. For small cone angles the induced friction force dominates the normal force, which tends to expel...

This chapter on disk brakes and clutches will consider annular contact disk clutches and both caliper and annular contact disk brakes, as illustrated in Figures 1, 2, and 3. Caliper disk brakes, as shown in Figure 1, are used on aircraft, automotive, industrial, and mining equipment. Their two main advantages compared to drum brakes are greater heat dissipation, and hence less fading, because of their open construction, and a more uniform braking action, due to self-cleaning by brake pad abrasion. Their main disadvantage is that they require a larger activation force than is required for drum brakes because they have...

Linearly acting drum brakes are those fitted with shoes which, when activated, approach the drum by moving parallel to a radius through the center of the shoe. Typical linearly acting drum brakes are illustrated in Figures 1–3. Analysis of linearly acting brakes includes those in which the centrally pivoted shoes are attached to pivoted levers, as in Figure 1. Including brakes of this design within the category of linearly acting brakes is justified if they are designed so that the applied forces on the shoes and linings act along the radii of the shafts that they grip when the brakes...

Typical externally and internally pivoted shoe brakes are shown in Figures 1 and 2. In all but extremely rare designs, equal forces act upon both shoes to produce equal applied moments about their pivots. External shoe brake control is usually through a lever system that may be driven by electromechanical, pneumatic, or hydraulic means. Internal shoe brake control is usually by means of a double-ended cylinder or a symmetrical cam. Calculation of the moments and shoe lengths to achieve a specified braking torque cannot be carried out directly when the two shoes are pivoted as shown in either of these...

Band brakes are simpler and less expensive than most other braking devices, with shoe brakes, as perhaps their nearest rival. Because of their simplicity, they may be produced easily by most equipment manufacturers without having to purchase special equipment and without having to use foundry or forging facilities. Only the lining must be purchased from outside sources. Band brakes are used in many applications such as in automatic transmissions (Figure 1) and as backstops (Figure 5—devices designed to prevent reversal of rotation), for bucket conveyors, hoists, and similar equipment. They are especially desirable in the last-mentioned application because their action...

1 Friction Materials Curves of the coefficient of friction as a function of load and of the speed differential between the lining and facings and their mating surface are no longer available from many manufacturers. Perhaps this is a consequence of the ease with which trial lawyers in the United States can collect large financial rewards for weak liability claims based upon often trivial, or unavoidable (due to physical limits on manufacturing tolerances), differences between published data and a particular specimen of the manufactured product. Furthermore, differences between published and operational coefficients of friction are beyond the control of the manufacturer because...

Clutch - Troubleshooting

Ly hợp ô tô là khớp nối giữa trục khuỷu động cơ với hệ thống truyền lực .Ly hợp dùng để ngắt , nối truyền động từ động cơ đến hệ thống truyền lực. Trong quá trình chạy xe, để việc chuyển số được êm dịu thì việc truyền công suất từ động cơ đến hộp số phải diễn ra từ từ, tránh sự đột ngột là nhờ bộ ly hợp. Bộ ly hợp này...

Hộp số dùng để thay đổi momen truyền đến các bánh xe chủ động đủ thắng sức cản của chuyển động ô tô máy kéo thay đổi quá nhiểu trong quá trình làm việc. Trong quá trình phát triển nền kinh tế quốc dân và phục vụ đời sống xã hội, việc vận chuyển hàng hoá, hành khách có vai trò to lớn. Với việc vận chuyển bằng ô tô có khả năng đáp ứng tốt...

Truyền động Các - Đăng dùng để chuyển động và mômen xoắn giữa các trục không nằm trên cùng một đường thẳng

Khi xe ô tô chuyển động thẳng trên đường bằng phẳng sức cản chuyển động ở bánh xe hai bên bằng nhau

Cấu tạo, bảo dưỡng và sửa chữa ô tô : Các hệ thống , tổng thành chủ yếu của xe ô tô

Body - san roof - on vehicle inspection

Side body moulding tools and supplies

Hood, front door , luggage compartment lid and back door

Trong bánh răng dẫn động của trục cam có một bánh răng phụ dùng để giảm tiếng ồn liên quan đến sự thay đổi mômen. Bánh răng phụ này luôn luôn được lò xo đẩy theo hướng quay, giảm khe hở của bánh răng bằng cách giữ ăn khớp với bánh răng dẫn động, để giảm tiếng ồn.