Flexure pivots · Single-ended or double-ended cantilever, diameter, torsional spring rate, load capacity in compression and tension, angular travel, hysteresis, weight and mounting
A flexure bearing replaces rolling or sliding contact with flat springs that bend elastically, giving limited rotation with no friction, backlash, wear or lubrication. Settle three things before asking for quotes: single- or double-ended mounting and diameter for your shaft and housing, the rotation range and spring rate the drive can work against, and the radial and axial loads, environment and life the pivot must meet.
Cylindrical flexure pivots and flexure bearings for limited-angle rotation in gimbals, positioners, sensors, optics and semiconductor and medical equipment. Ball and roller bearings, flexible shaft couplings, compliant-mechanism stages designed as one machined part, and slewing bearings are outside this page.
01
C-Flex describes its pivot bearings as cylindrical, limited-rotation bearings that are frictionless, backlash-free, self-centring and repeatable, with low hysteresis, suitable for vacuum, needing no lubrication or maintenance, and with indefinite life at undiminished accuracy. They come as single-ended and double-ended cantilever bearings for gimbals, tensioners, positioners, lever actuators, sensors, optics, semiconductor and medical equipment. Each bearing is two stainless steel sleeves held by three leaf springs on two planes, so the sleeves never touch; an extra central sleeve makes the double-ended version with two pivot arms. [1]
The double-ended range runs in ten sizes from 1/8 inch (0.1250) to 1 inch (1.000) diameter, each in 10, 20 and 30 series of rising torsional spring rate, with load capacities listed separately for compression (Lc) and tension (Lt). C-Flex's weight chart lists 0.1 g for the smallest sizes up to 68.8 g for the largest single-ended J30. [1] [2]
Give the supplier single- or double-ended mounting, diameter and length, rotation range, torsional spring rate, radial and axial loads in each direction, centre-shift tolerance, cycle count and frequency, operating temperature and environment (vacuum, cleanroom), material, mounting method and quantity.
02
C-Flex states that its pivots offer high radial and axial stiffness, come in low, medium or high torsional spring rates from 0.0003 to 7.8023 lb-in/degree, and support maximum deflection of ±30°, with custom designs up to ±50° travel, load capacities over 1,600 lb and materials such as Hastelloy X and titanium. The spring rate and load capacity depend on the length, width and thickness of the internal spring beams: higher rotation angles need thinner springs, which lowers both spring rate and load capacity. At 1/4 inch, for example, the DD-10, DD-20 and DD-30 list torsional spring rates of 0.0018, 0.0148 and 0.1185. [1]
Editorial calculation: at 1/4 inch the spring rate rises about eightfold from each series to the next (0.0148 ÷ 0.0018 ≈ 8.2; 0.1185 ÷ 0.0148 ≈ 8.0). A DD-20 at 0.0148 lb-in/degree needs 0.0148 × 30 ≈ 0.44 lb-in (about 0.05 N·m) of torque to hold it at 30°; the drive must supply that restoring torque on top of the load's own torque, while a stiffer DD-30 at 0.1185 would need about 3.6 lb-in. [1]
C-Flex bases cycle life on the fatigue limit of the spring material, rating bending and load stresses so that cycle life is statistically infinite; spring materials include martensitic and precipitation-hardening stainless steels, Inconel, Hastelloy and beryllium copper. [1]
Editorial note: because a flexure pivot returns to centre under its own spring rate, it suits oscillating and limited-angle motion; it does not suit continuous rotation. [1]
03
No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
Ask each supplier for the spring rate, load capacity in compression and tension with their units and test conditions, allowed angle at your load, centre shift and fatigue life data. [1]
04
A paper by F. A. Seelig of the Bendix Corporation, held in NASA's technical reports archive, shows a complete flexural pivot specification from the Lunar Orbiter, where stock cantilever pivots carried the gimbal of a 100-lb thrust engine. The specification set a rate of motion of 0.05 to 10 deg/s, nominal angular motion of ±4 deg, a torsional spring rate through maximum angular motion of 13 lb in./rad ±10%, a radial load of 200 lb maximum and 110 lb nominal, and an axial load of 35 lb maximum. Life was written as load cases: 5,000 nominal angular cycles at maximum temperature and nominal radial load, and 200 nominal angular cycles at maximum temperature with maximum radial and axial load. Seelig notes the pivots were bought from stock with a load test before shipment. [3]
Seelig links construction to load. Brazed pivots with flat flexures are adequate when temperature and load conditions are moderate, while designs carrying high transverse loads use I-beam flexures with a one-piece tubular core, welded so the heat-affected zone stays away from the highly stressed part of the flexures. He sets core thickness at least equal to flexure thickness for welded construction, with a thicker core for brazed construction. [3]
Two failures in the paper are worth turning into acceptance terms. On the ERNO engine gimbal, housing-to-core welds passed acceptance load tests but failed in a static load test once installed in the customer's hardware. On the DCTM test stand, housing thickness governed radial stiffness and the pivot diameter had to be increased. Ask the supplier to state the joining method and to load-test in a fixture that matches your mounting. [3]
05
Riverhawk Company's engineering data for its Free-Flex flexural pivot (flat springs crossed at 90° supporting counter-rotating sleeves; stock diameters from .125 in to 1.0 in; radial loads to 1600 lb) gives centre shift as a factor table: multiply the pivot diameter by the factor for the deflection angle. Its worked example is a 0.6250-inch pivot at 4 degrees: 0.6250 × 0.001 = 0.000625 inch. [4]
Radial stiffness depends on the mounting. Riverhawk measured its stiffness table on cantilever (5000 series) brazed pivots loaded at the mid-point of the unsupported half at 0 degrees deflection. For a double-ended (6000 series) pivot it says to multiply the radial values by 2.5, with no change in axial stiffness; for cantilever pivots used as a pair and connected very stiffly, multiply by 1.25 for each pivot. The data is for reference only and not guaranteed, so ask for values measured in your load direction and mounting. [4]
Riverhawk lists an ambient temperature range of -400°F to +1200°F and radial stiffness up to 100,000 lb/in; for elevated ambient temperature it electron-beam welds the springs to the body instead of brazing them. It reports a pivot cycled for over 12 billion cycles over twenty years. [4]
06
This is a functional reference built from the sources cited; it is not a full specification.
07
A flexure bearing quotation needs values for your design. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Bearing Diameter | 1/8 to 1 inch. [1] | mm; tolerance. |
| Bearing Width | Length set by size. [1] | mm. |
| Radial Stiffness | High radial and axial stiffness stated. [1] | N/mm. |
| Angular Travel Range | Up to ±30°; custom to ±50°. [1] | °. |
| Load Capacity | Lc and Lt by size; custom over 1,600 lb. [1] | N each direction. |
| Operating Temperature | Not stated in the reviewed sources. | °C. |
| Material | Stainless steel sleeves; PH or martensitic stainless, Inconel, Hastelloy, BeCu springs. [1] | Material. |
| Surface Finish | Not stated in the reviewed sources. | µm Ra. |
| Fatigue Life | Rated to fatigue limit; statistically infinite. [1] | Cycles at angle. |
| Weight | 0.1–68.8 g. [2] | g. |
| Precision (Hysteresis) | Low hysteresis stated. [1] | Value. |
| IP Rating | Not applicable to an open pivot. | — |
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Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Style: [single-ended; double-ended] Size: [diameter; length] Motion: [±°; cycles; Hz] Stiffness: [torsional rate] Loads: [radial; axial; compression; tension] Environment: [°C; vacuum; cleanroom] Quantity: [units]
No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
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A limited-rotation bearing that bends elastically instead of rolling or sliding, so it is free from friction, backlash and wear and needs no lubrication. [1]
C-Flex states its pivot bearings support maximum deflection of ±30°. [1]
C-Flex lists torsional stiffness from 0.0003 to 7.8023 lb-in/degree across sizes and series. [1]
C-Flex lists diameters from 1/8 to 1 inch, weighing 0.1 to 68.8 g. [1] [2]
The Lunar Orbiter specification in a Bendix paper archived by NASA lists rate of motion, temperature, nominal angular motion, cycle life at stated loads, torsional spring rate with a ±10% tolerance, and maximum radial and axial loads. [3]
Riverhawk's Free-Flex engineering data gives centre shift as the pivot diameter times an angle factor, from 0.00009 at 1° to 0.0200 at 20°; its example 0.6250-inch pivot shifts 0.000625 inch at 4°. [4]
Sources checked 2026-10-11. C-Flex Bearing Company's pivot bearing product page and weight chart are used to show what a flexure bearing specification covers; values for your order must come from the supplier's specification sheet.
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