Vescor Catalog > Pump Motor Adapter/Dampening Flanges > Dampening Flanges

Dampening of structure-borne noise by means of elastic dampening elements

Noise control is still one of the most important tasks in the field of hydraulics. During the past few years there has actually been some progress regarding the reduction of primary noise generation, i.e., the hydraulic pumps have become more quiet, however, the demands for quiet machines have become further intensified and will continue to do so. Thus the mere selection of a quiet hydraulic pump or a quiet electric motor is not sufficient in most cases, but some suitable secondary measures have to be performed in order to optimize the noise behavior of the complete unit.

The measures for the reduction of structure-borne noise form an important part of the noise reduction of hydraulic power units. The hydraulic pump and the electric motor do not just directly dispel airborne noise, but they also transmit structure-borne noise vibrations, which pass through the power unit and are then dispelled as a airborne noise by the surfaces. Thus the reduction of structureborne noise by means of corresponding members is an effective secondary measure for noise reduction.

Measures for the reduction of structure-borne noise

Depending on the structural shape of the hydraulic power unit the measures for dampening the structure-borne noise are necessary directly at the pump as well as between the pump unit and the hydraulic reservoir.

Dampening Flange

The dampening of structureborne noise directly at the main noise generator "hydraulic pump" by means of the dampening flange is sure to become the standard in the field of hydraulics. This measure is especially effective, as the dampening flange is positioned in the power flow of the torque and the vibrations produced by the pump, hold a high energy density. The components (pump/motor adapter with dampening flange and electric motor) thus experience a clearly reduced introduction of structure-borne noise and accordingly they dispel less airborne noise.

Successful measures for the reduction of structure-borne and airborne noise show that it is worthwhile to invest some expenditure in tests and thus to optimize the effect of dampening elements. Naturally, the extent of the possible reduction of the airborne noise is limited. Investigations have revealed that the noise level dispelled by the hydraulic power unit may exceed the values of the sole pump noise by 10 to 12 dB (A). This also depends on the size of the power unit, i.e. on the size of the surfaces dispelling airborne noise. As the complete power unit constitutes an oscillatory formation with many different natural frequencies and surfaces dispelling airborne noise, one can estimate the expected extent of an airborne noise reduction by means of hydraulic elements dampening the structure borne noise, however, it can not be predicted exactly.

Due to substantial investigations and measurements in practical operation the following approximate values can be presumed:

1. Pump motor adapter with dampening flange: 3 to 6 db(A)
2. Dampening bar VSM: 3 to 4 db(A)
3. Pump motor adapter with dampeningflangeand dampening bar VSM: 6 to 8 db(A)

The maximum values can be achieved when it is possible to reduce the resonances in the power unit with the aid of a damping element, these resonances might arise, because the main exciting frequency of the hydraulic pump corresponds to the natural frequency of machine parts with large surfaces.

DAMPENING FLANGE

The flexible dampening flange renders possible and efficient structure-borne noise separation directly at the hydraulic pump.

Average expected reduction of 3 - 6 dBA

DAMPENING BAR

The flexible dampening bar prevents the transmission of structureborne noise between pump/motor and aggregate.

Average expected reduction of airborne noise 3 - 4 dBA

DAMPENING FLANGE and DAMPENING BAR

Both dampening flanges and dampening bars render possible and optimum of structure-borne noise dampening of pump and motor.

Average expected reduction of airborne noise 6 - 8 dBA

• Locked vulcanized design - not bolted together
• High weight loading possible (with multiple pumps)
• Excellent dampening properties
• Excellent resistance against ozone and oil
• Integral sealing lip - no additional sealing required
• Fully machined to most SAE 2 & 4 bolt and ISO 2 & 4 bolt mounting flanges
• Easily bolts to Vescor Dampening Flange Adapter
• Can be mounted horizontally or vertically
• Furnished as complete assembly only

EXAMPLE: Dampening Flange Selection

Pump = Rexroth AA4VSG71
Pump Weight = 132 lbs. (FG)
L(x) = Distance of the Center of gravity
L(P) = the length of the pump
L(x) = 2/3 L(P)
L(x) = 2/3 12.12 inches
L(x) = 8.08 inches

If your required model or dampening flange is not known, or you wish to verify your selection, Please provide Vescor with the following information:

1. Motor HP with Frame Size
2. Pump Manufacturer and Complete Model Number
3. Pump Weight
4. Coupling Manufacturer and Model

If your required model or dampening flange is not known, or you wish to verify your selection, Please provide Vescor with the following information:

1. Motor HP with Frame Size
2. Pump Manufacturer and Complete Model Number
3. Pump Weight
4. Coupling Manufacturer and Model

If your required model or dampening flange is not known, or you wish to verify your selection, Please provide Vescor with the following information:

1. Motor HP with Frame Size
2. Pump Manufacturer and Complete Model Number
3. Pump Weight
4. Coupling Manufacturer and Model