PRODUCTS SPRINGS & SHOCK ABSORBERS
ANTI-VIBRATION MOUNTS RANGE EXTENDED TO MEET DEMANDS
In response to customer demand, WDS has extended its range of anti-vibration mounts, with marine engine mounts and cone cab mounts. Anti-vibration mounts act as dampeners or shock absorbers in a wide range of applications, including isolating engines, motors, compressors, pumps and fans that naturally create vibrations. They can also be used to isolate plant and machinery such as vibratory feeders, polishers, mixers, saws, drills and other machine tools. As shock absorbers they are a popular choice for bump stops on conveyors and as stops to limit the travel of hinged doors and panels. With a low profile design, the marine
engine anti-vibration mounts are designed
to support the thrust loads generated by propeller drives. The cone cab mounts are intended for use with compressors, engines and pumps. Their geometry is optimised to absorb high shear and compression stresses while accommodating axial deflection. The company’s anti-vibration mount range is well
established. Most use a rubber stop of 55 Shore hardness to absorb the energy, although softer 45 Shore and stiffer 75 Shore stops are available as options. The stops are typically cylindrical, but other shapes are available. Adjustable levelling feet with anti-vibration pads are also included in the range. Anti-vibration mount products from WDS are available from
stock with next day delivery available on selected products. WDS Component Parts
www.wdsltd.co.uk
DAMPED ABUTMENT CLIP HELPS ENSURE SMOOTH BRAKE OPERATION
Trelleborg Sealing Solutions has developed a damped abutment clip (or ‘slipper’) that can be tailored to any sliding caliper brake system to ensuring its smooth operation with no shake or rattle. According to the company: Imagine a carefully
engineered ‘layer cake’ of stainless steel and rubber holding the brake pad in place. Sandwiched between the brake pad ‘ear’ and contact points in the anchor bracket, the abutment clip dampens the clunk or low-frequency noise by decoupling the pad ear, isolating it from the anchor bracket and preventing in-plane energy from being transmitted to the calipers. It also enables the easy retraction of the pad on the release of brake pressure, reducing the risk of residual drag. Abutment clips have traditionally been made from uncoated stainless steel, but as
car engines have become quieter, there has been a growing demand for noiseless braking systems with rubber-coated clips. So, Trelleborg makes clips with a temper-rolled stainless steel core coated with PTFE (polytetrafluoroethylene) and rubber. Flexible, nonstick, nonreactive and heat-resistant, PTFE minimises friction, optimises brake performance and enhances the robustness and durability of the brake pad. This means the pad can slide freely in the caliper which, in turn, makes for lower fuel consumption levels. The best performance of Trelleborg’s damped slippers is typically seen with
frequencies ranging from 1-5kHz. In some applications they also perform well at higher frequencies, particularly when the frequency of the noise coincides with the brake disc in-plane vibration frequency, the company adds.
Trelleborg Sealing Solutions SPRING SPECIFICATION CONSIDERATIONS
There are a number of factors that need to be considered when specifying springs. To start, Hooke’s Law is a principle of spring design relating to Load and Deflection. It states that a restoring force due to a spring is proportional to the distance the spring is deflected and acts in the opposite direction. Another principle of spring design is Spring Rate (R), which is the ratio of force per unit of deflection. A further consideration is direction of wind: A coil spring can be wound in a
left-hand or right-hand direction, in the same way as a screw thread; and this can be particularly important depending on how the spring will be used. As an example, when one spring is required to operate within another spring, the springs should be designed to wind in opposite directions. Spring ‘squareness’ relates to the angular difference between the outside of the
spring diameter and the straight edge of the spring when it is stood on its end; while spring ‘parallelism’ relates to how parallel the ends of the spring are to one another. The designer will also need to consider the spring diameter – either the outside
diameter (OD), which is important when the spring is to be used in a cavity, or the inside diameter (ID), which is important for springs required to work over a rod or shaft. Free length, meanwhile, is the overall spring length. Other considerations are the spring index – the ratio between the mean
diameter and the diameter of the wire. A high index spring has a smaller wire and a larger spring diameter, such as a Lite Spring, whereas a low index spring has a larger wire diameter and a smaller spring diameter, such as a Die Spring. Designers will also need to think about the Load (P), which refers to the force
required to compress the spring to a specific height; its solid height – the dimension of the spring when the coils are closed; the number of coils; and the spring pitch, which relates to the distance between the centres of adjacent coils. Finally, the spring set needs to be considered. Before its first compression the
spring’s free height may be longer than required, which can be corrected in one of two ways. The spring can be designed and built with a free length that includes allowance for set, allowing for length loss when the spring is compressed for the first time, or an additional manufacturing step known as ‘removing the set’ or ‘presetting’ can be taken. Also known as a ‘set spring’, this involves compressing the spring to the solid height. A set spring will have a new free length that will remain consistent through future compression cycles.
Lee Spring 10 APRIL 2019 | DESIGN SOLUTIONS
www.leespring.com
www.tss.trelleborg.com/en
INDEXING PLUNGERS LOCK PIECES OF MACHINERY FOR ADJUSTABLE POSITIONING
Indexing plungers suitable for a wide variety of industrial applications are now available from Ruland. These use the force of a spring to apply pressure, allowing the plunger pin to remain nested in a receptacle. This means two or more elements of equipment can be aligned or fixed into a determined relative position. Ruland indexing plungers feature a pull knob that
partially encloses the top of the plunger body, allowing less debris to enter the mechanism for consistent performance and longer life. They are commonly used in industrial equipment for positioning and holding, in medical equipment for height adjustments, and in machine guard doors to prevent them from being opened accidentally. The products are available with or without lock-out, and
in standard and mini types in a variety of inch and metric thread sizes. Mini indexing plungers have a shorter threaded body than the standard indexing plungers, making them suitable for thin walled sheet metal applications. The longer threaded body of the standard indexing plungers makes them ideal for thick walled metal applications. However, standard indexing plungers can also be used in thin walled sheet metal applications thanks to a locknut.
Ruland Manufacturing
www.ruland.com
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