Enclosed Spring Mounts

Where a preference exists for the enclosed captive spring style of mount, we have responded by adding a new range to complement the existing Vibrostop open spring range.

For ultimate isolation performance this new range includes the DM and DH styles which provide spring compression up to 50mm.

To eliminate spring buckling, duplex springs sets are arranged in series separated by a steel plate

Un-necessary pre-travel is eliminated and stability is assured in this range as the mount is assembled in a pre-compressed condition.  This range also features level adjustment such that the installation can be maintained perfectly level even if all mounts are not subject to exactly the same loading.  99% isolation can thus be achieved at frequencies as low as 14Hz (840rpm)

The range includes single and multiple spring mount to suit loads from 10 to 1650Kg.  Throughout the range, the design deflection is either 25 or 50mm providing high and predictable levels of vibration isolation even at relatively low frequencies.  To achieve these high deflections, all mounts are pre-compressed during assembly by 10mm or 25mm in the case of the high deflection.  The maximum actual compression in these mounts is therefore actually either 25mm or 50mm in the case of the high deflection mounts.

Typical Applications

This style of mount is used frequently in applications where high levels of vibration isolation are necessary such as in air handling systems, motor/generator sets and motor/pump combinations within, or on top of occupied buildings.  A key application would include hospital theatre and metrology laboratory air handling units and motor driven fan units where noise and vibration must be precluded.

Dimensions and Data

Model types include the following:

WSAA             Single spring enclosed isolator                     10 to 40Kg

WSA-M           Multiple Spring Isolator                                 40 to 660Kg

WSA-DM        Multiple Spring Isolator-high deflection         40 to 660Kg

WSA-H           Multiple Spring Isolator, heavy duty              500 to 1650Kg

WSA-DH        As above with, high deflection                       500 to 1650Kg

Notes:

• Deflection under load prior to levelling is given by the formula: (A/B)-C where

A = Load in Kg

B = Spring rate in Kg/mm

C = Pre compression in mm

Example: If a load of 950Kg is placed on the WSA-1000DH, the deflection would be 22.5mm from the unloaded height.  The actual compression of the spring mount for the purposes of vibration isolation calculations would be 47.5mm

• From the minimum loaded height the mounts can be adjusted to the unloaded height less 5mm.
• Compressing beyond the minimum height (i.e. exceeding the spring rating) will reduce the spring life and may result in reduced isolation efficiency or, in extreme cases, premature failure.
• Adjusting to the maximum free height will reduce isolation efficiency as the load will not be fully supported by the springs.

When supplied, the springs are already partly compressed, tending to extend the mount to its maximum height.

When loaded, the whole mount will be compressed.  It is important that the load is applied evenly and without sideways (shear) loading during installation.

Once all mounts are in place and partly compressed, the jacking/adjusting screw can then be used to firstly level the mounts and then secure them to the load using the locking nut provided.

During this process where unequal loads are experienced by the mounts, it is important to start with the mount which has deflected the most.  This can be checked by measurement or using a spirit level (provided that the floor is also level).

In this above picture, the springs are deflected to exactly the same length as in the central picture.  The upper spring ‘cup’ has simply been jacked up using the adjusting bolt to increase the height of the complete spring mount assembly