A unidirectional seat is a valve seat designed to seal the pressure source in one direction only. SPE - Single Piston Effect Seats (Self Relieving Seats) Trunnion mounted ball valves with two unidirectional (self-relieving) seats are designed for blocking the fluid in both directions. Each seat is sealing in one direction, from the valve ends to · Starting with the back spring on the middle vertical row, pull the first strand of spring twine under the second rung and tie a single knot around it as you hold it tightly in position. Move on to the other side of the same spring, and tie a knot around the top rung. Continue tying a single knot on the top of both sides of each spring Spring Seat P-Pad Harley Sportster Chopper Bobber 10x13 Brown Dist Leather. $ Description Brown Distressed Leather Chopper Bobber Harley Spring Solo Seat, and p-pad. We start with 1/8" steel pan built in our shop. The pan is very thick, rigid, and sturdy. The pan has a kickup View full product details
upholstery basics: constructing coil seats — part I – Design*Sponge
An end face mechanical seal is a device intended to prevent or minimize leakage from a vessel through the clearance around a rotating shaft entering that vessel. Perhaps the most common example is the end face mechanical seal used in the water pump of an automobile engine. Most pumps used in petroleum refineries, chemical plant and pipelines also use end face mechanical seals, single spring seat.
The simplest possible mechanical end face seal consists of a shoulder on a rotating shaft which rubs against a stationary case, single spring seat. This concept is shown in Figure 3. As with packing or any bearing material, lubrication and cooling are required to prevent heat buildup and wear.
Hydraulic pressure tends to force fluid between the faces and provide a lubricating film but the face separation must be kept very small to minimize leakage, single spring seat.
Cooling is provided by the surrounding liquid. The conceptual design shown in Figure 3 is very simple, but it demonstrates the basic principle of the end face mechanical seals. Of course, it has functional drawbacks which must be addressed. A major shortcoming of the conceptual design shown in Figure 3 is that there will be always be some shaft movement during operation of the equipment.
This movement is a result of manufacturing tolerances, vibration, hydraulic forces and wear. Shaft movement may single spring seat decrease face separation, causing gross face contact and wear, or increase face separation, causing increased leakage.
Seal face leakage is governed by many variables, single spring seat, but the dominant variable is face separation. A variation of a few micro-inches millionths of an inch in the face separation can cause significant changes in leakage. Unfortunately, shaft movement can amount to several thousandths of an inch. A practical approach to overcoming shaft movement is to mount one of the seal faces in a flexible manner so that it can move axially, single spring seat.
Obviously a desirable feature, this single spring seat is a prerequisite for effective seal design. Figure 4 shows an improved seal as compared to Figure 3. In Figure 4, The sealing shoulder on the shaft has been removed and replaced with single spring seat component which is not permanently attached to the shaft.
This component is called the primary ring. Since the primary ring and the shaft are two separate parts, single spring seat, an additional sealing device must be used to prevent leakage between the shaft and primary ring.
The flexibly mounted primary ring can compensate for the small variations in movement on the axial plane. It can also adjust for seal face wear. Figure 4 is a very simple mechanical seal but it illustrates the concept used by the majority of mechanical seals. Of course, some additional components are required to preload the faces, transmit torque and provide ease of installation. As will be seen later, the design of these components may vary considerably according to the required service for the seal.
In addition, the assembled components themselves may be arranged and oriented in various ways to accomplish varying degrees of sealing, reliability and redundancy. In a mechanical seal, the primary leakage path is between the seal faces. Naturally, increasing the face separation increases the leakage. In fact, as will be shown later, doubling the face separation can increase the leakage rate by a factor of eight!
This relationship between leakage and face separation provides a powerful incentive for minimizing face separation. In modern mechanical seals, face separations are so small on the order of a few microns that the single spring seat rate is affected by the surface roughness.
The effective face separation is a combination of the surface roughness of the two mating parts and the fluid film thickness. This concept is illustrated in Figure 6. The seal manufacturer can control the initial surface finish by lapping and polishing. A typical seal face is flat to within 23 millionths of an inch, single spring seat. This degree of flatness is so small that refracted light rays must be used to measure it, single spring seat.
The fluid film is established during initial start-up of the seal by hydraulic forces. The principle of establishing a fluid film is essential to all seal designs. Most mechanical seals are designed to operate in liquids; these seals require a liquid film.
Designing a seal to operate on a gas film is much more complex. Whether the film is gas or liquid, it reduces the gross contact between the rotating component and single spring seat stationary component. It also provides lubrication to reduce friction and wear, single spring seat. Without a stable fluid film, gross rubbing contact could damage the faces. Mechanical seals may be classified by their design features and the arrangement of those features.
Figure 7 illustrates the classification of mechanical seals. Figure 7. Classification of mechanical seals. All mechanical seals contain both rotating elements and stationary elements which include five basic components:. The Design classification considers the details which enter into the features of these components. Some examples of these features are balance, face treatment, rotating element, springs, secondary sealing elements and drive mechanism. In general, these design features are not completely independent; that is, emphasis of a particular feature may also influence other features.
For example, selection of a particular secondary sealing element may influence the shape of the primary ring. By definition, the primary ring is the flexible member of the mechanical seal. The design of the primary ring must allow for minimizing distortion and maximizing heat transfer while considering the secondary sealing element, drive mechanism, spring and ease of assembly, single spring seat.
Many primary rings contain the seal face diameters, although this is not a requirement of the primary ring. The primary ring always contains the balance diameter. Balance ratio is defined as the ratio of the hydraulic closing area to the hydraulic opening area. This ratio is customarily expressed in a percentage. Figure 8 illustrates the concept of balance. In a seal, hydraulic pressure acts on the back of the primary ring; the resulting force pushes the faces together.
Single spring seat force is called the closing force and this area the closing area. Similarly, any pressure between the seal faces creates an opening force which tends to separate the faces. Therefore, the face area is also called the opening area. The balance ratio is simply the ratio of the closing area to the opening area. As shown in Figure 8, the area above the seal face outside diameter is disregarded when the closing area is computed.
This area is not considered because the pressure is the same all around it; consequently the contribution of the resultant of the hydraulic forces on this area is zero. When the closing area is reduced, the closing force is reduced proportionally; this feature can be used to advantage when designing a seal.
However, for a seal shape such as shown in Figure 8, the closing area will always be greater than the opening area. In order to make the closing area less than the opening area, the shape can be changed as shown in Figure 9. For a given pressure, balanced seals have less face load than unbalanced seals. Therefore, balanced seals are normally used in higher pressures than unbalanced seals.
Primary ring shape. The shape of the primary ring may vary considerably according to the incorporation of various design features. In fact, the shape of the primary ring is often the most distinct identifying characteristic of a seal.
Figure 10 shows four examples of typical primary ring shapes. Figure single spring seat represents a primary ring associated with elastomeric bellows seals. This primary ring has been optimized to take advantage of the elastomeric bellows and a large, single spring. Figure 10b represents a primary ring with an inserted seal face.
Insert faces must be designed with care because temperature differentials can cause differential expansion between the adaptor and the primary ring. Insert designs single spring seat also have problems associated with mechanical stress and distortion. Single spring seat 10c and 10d show how the shape of the primary ring is influenced by the secondary sealing element.
Figure 10c is a primary ring designed to work with a wedge, single spring seat. Figure 10d is designed to work with an O-ring, single spring seat. Also, Figure 10c shows an unbalanced shape while Figure 10d is a balanced shape. Face Treatment. The most common seal face design is a plain, flat surface but there are many special treatments designed for specific applications.
Figure 11 shows some of the more single spring seat face treatments. The plain, flat face is most common. In general, face treatments are a means of modifying the pressure distribution between the seal faces. The most common objective is to increase the opening force and thereby reduce the magnitude of the mechanical contact.
Face treatments may be considered to produce hydrostatic or hydrodynamic forces, single spring seat. Hydrostatic forces do not depend on the rotational speed whereas hydrodynamic forces vary with the rotational speed. The simplest face treatment is a plain face that is not flat. This design produces forces that are primarily hydrostatic.
Figure 11b shows an example of a face that is lapped so that it tends to touch the mating ring at the inside diameter. This means that the leakage path is converging. Although this is a simple concept, single spring seat, it is actually difficult to lap the required taper with the desired accuracy.
Custom Motorcycle Seats & Components | Motorcycle Saddles Kit & Accessories – Lowbrow Customs
The length springs needed depends on several things, including the frame dimensions, type of solo seat, and style of seat spring mountss being used. Ideally the seat is mocked up and a measurement can be taken to determine what length seat springs are needed. You do not want to slide back while riding, so the solo seat should be mounted so that it is parallel to the ground. Most solo seats have a Acouto Motorcycle Solo Seat Springs 1 Pair Motorcycle Modified Seat Mount Spring 2 Inch Spring Bracket Hardware Mount Kit for Chopper Bobber for Honda for Yamaha out of 5 stars 27 $ $ Harley Davidson seat custom designed to fit you and provide a comfortable ride. Seats for Sportster. These kits are adaptable to most spring applications. Valve Springs: What you should know about them. distance from the spring seat on the cylinder head to. single springs to high performance dual or triple
Keine Kommentare:
Kommentar veröffentlichen