Leveling Feet GN 248 (LW.A)

d₁	d₂	l₁	d₃	d₄	l₂ min.	max.	l₃	l₄	s Square	Static load in N	Stiffness in N/mm	max. compression in mm

80	M 12 x 1,25	133	60	72	35	46	32	10	7	5000	2500	2
120	M 16 x 1,5	144	80	109	40	51	36,5	10	9	10000	4000	2,5
160	M 20 x 1,5	188	100	150	50	63	43,5	10	12	20000	9000	2,2
200	M 20 x 1,5	198	130	186	60	73	54,5	10	12	40000	15000	2,7

Degree of isulation

Interference frequency [Hz]:
is the frequency emanating from a machine,
e.g. from the machine main shaft speed [rpm].

Static load F [N]:
is the load acting on each vibration-dampening element (levelling foot).

Degree of insulation [%]:
measure for absorbing the interference frequency (dampening)

Compression s [mm]:
is the change in the height of the dampening element (spring excursion).

Stiffness R [N/mm]:
is the load causing the dampening element to be compressed by 1 mm (spring rate).

Determining the suitable levelling foot and the achievable degree of insulation

The first step is to determine the static load F for each levelling foot. With favourably arranged levelling feet and therefore an evenly distributed load F, this value is calculated using the following equation:

Force due to weight of the machine [N] / Number of levelling feet

= static load F [N] for each levelling foot

Use the calculated static load F to select a levelling foot from the table, making sure that the static load F lies as close as possible to the static load capacity without exceeding it. The associated stiffness R of the selected levelling foot is also taken from the table.
The actual compression is then calculated using the equation below:

Static load F [N] per levelling foot /
Stiffness R [N/mm]

= actual compression s [mm]

Starting from the calculated actual compression s, the achievable degree of insulation as factor of the interference frequency can now be taken from the graph shown above.
To optimise the achievable degree of insulation, the number of levelling feet may be changed such that the static load F for each foot is as close as possible below a load capacity value given in the table.
This will increase the compression s which, in turn, results in a higher degree of insulation.
In general it can be said that medium to high frequencies can be very well insulated with sufficient compression.

Example

Static load F (machine weight) = 48,000 N, number of feet = 4, ergo: static load per foot = 12,000 N
Selected foot: d₁ = 160, static load capacity 20,000 N, R = 9,000 N/mm
Resulting in an actual compression s of:

12,000 N (static load/foot) /
9,000 N / mm (stiffness R)

= 1.3 mm

With an interference frequency of 20 Hz (1,200 rpm), the above graph delivers a degree of insulation of only about 20 %.

To optimize, the number of feet may be increased to 5, resulting in a static load per foot of 9,600 N. A levelling foot whose static load capacity is closer to the new result may now be selected.
Newly selected foot: d₁ = 120, static load capacity 10,000 N, R = 4,000 N/mm
This results in an actual compression s of:

9,600 (static load/foot) /
4,000 N/mm (stiffness R)

= 2.4 mm

With the same interference frequency of 20 Hz (1,200 rpm), the above graph now delivers a degree of insulation of approx. 75 %.

Selected Part (How to order)

Part number

Total (net)

41,69 €

plus VAT 7,92 €
gross 49,61 €

In stock

ELESA Code: 415111

Description: LW.A-80-M12x1,25x120

Weight: 0,500 kg

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RoHS: Yes

This article is RoHS-compliant in application of Annex III., which means it complies with EU Directive 2011/65/EU, including extension (2015/863/EU), for restricting the use of certain hazardous substances in electrical and electronic devices. The Directive regulates the use of hazardous substances in devices and components. The implementation in national law is summarily described with RoHS(Restriction of (the use of certain) hazardous substances).

Customs tariff number

40169991

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All prices in accordance with our price list No. 56, valid from 1 September 2024, plus VAT only valid for Germany.