Constant Force Springs Stainless Steel

Part Number	CAD	t (mm)	W (mm)	L0 (mm)	In/Ext (mm)	Wo/Ext (mm)	P (N)	Di (mm)	D0 (mm)	A (mm)	d (mm)	FL	Qty
CF0120038		0.08	4.75	305	9.54	269	1.70	5.33	7.62	2.54	2.4	4000	Add
CF0150049		0.10	4.75	381	13.17	333	2.20	7.36	10.16	2.54	2.4	4000	Add
CF0150065		0.10	6.35	381	11.36	333	2.90	6.35	10.16	4.75	3.3	4000	Add
CF0150050		0.10	6.35	381	15.49	305	2.20	8.64	10.16	9.50	3.3	4000	Add
CF0180023		0.10	6.35	457	24.30	383	1.03	13.50	15.75	4.75	3.3	25000	Add
CF0150083		0.10	7.90	381	12.72	333	3.70	7.11	10.16	4.75	3.3	4000	Add
CF0170103		0.13	7.90	432	16.82	372	4.60	9.40	12.70	4.75	3.3	4000	Add
CF0180036		0.13	7.90	457	31.50	363	1.61	17.50	20.00	4.75	3.3	25000	Add
CF0180075		0.13	9.40	457	19.05	381	3.34	10.67	12.70	9.50	3.3	4000	Add
CF0250043		0.13	9.50	635	29.70	541	1.92	16.50	20.00	4.75	3.3	25000	Add
CF0210025		0.15	9.40	533	51.56	305	1.11	28.70	34.54	9.50	3.3	40000	Add
CF0220112		0.15	9.40	559	23.37	457	4.98	12.95	15.75	9.50	3.3	4000	Add
CF0240148		0.15	9.50	610	20.46	536	6.60	11.43	15.70	8.70	5.0	4000	Add
CF0250052		0.15	9.50	635	32.40	550	2.30	13.20	18.00	8.70	5.0	25000	Add
CF0250198		0.15	12.70	635	20.46	557	8.80	11.43	16.50	8.70	5.0	4000	Add
CF0250070		0.15	12.70	635	36.00	524	3.10	20.00	23.50	8.70	5.0	25000	Add
CF0250037		0.18	12.70	635	59.94	381	1.65	33.27	40.13	9.50	3.3	40000	Add
CF0260162		0.18	12.70	660	26.92	533	7.21	14.99	19.05	9.50	3.3	4000	Add
CF0300263		0.20	12.70	762	26.85	663	11.70	15.00	21.00	8.70	5.0	4000	Add
CF0330094		0.20	12.70	838	48.60	691	4.20	27.00	31.25	8.70	5.0	25000	Add

CONSTANT-FORCE SPRINGS

Constant-force springs are a very special variety of extension spring. They consist of a spiral of strip material with built-in curvature so that each turn of the strip wraps tightly on its inner neighbour. When the strip is extended (deflected) the inherent stress resists the loading force, just as in a common extension spring, but at a nearly constant (zero) rate.

The constant force spring is well suited to long extensions with no load build up. In use, the spring is usually mounted with the ID tightly wrapped on a drum and the free end attached to the loading force, such as in a counterbalance application. The relationship can be reversed, however, with the free end mounted stationary and the spring itself providing the working force, as with carbon brushes in electrical apparatus.

NOTE: Be sure to allow at least 1.1/2 cols of material on the drum at full extension. The spring ID will wrap tightly on the drum so that in most applications no fastening method on the drum is required.

MATERIAL

Type 301 stainless steel.

HOW TO MULTIPLY CONSTANT FORCE SPRING LOAD

Considerable flexibility is possible with constant-force springs because the load capacity can be multiplied by using two or more strips in tandem or back-to-back, as illustrated.

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