Ask a load cell how hard something is pushing and it answers in volts. Inside is a purposely shaped piece of steel wearing a set of gauges; squeeze it and it yields by an amount no eye could catch, the gauges register that yielding, and the bridge behind them renders it electrically. A certificate signed against known weights is what converts the answer into pounds.
Simple enough at any scale. What is not the same at any scale is everything surrounding the sensor once the forces get genuinely large.
Two hundred tons is not a bigger version of two hundred pounds. It is a different working environment with different rules. The energy stored in a loaded structure at that level makes a failure violent rather than merely inconvenient, so fixture design becomes a safety matter and not just a metrology one. The test frame, the platens, the supporting steelwork — all of it deflects measurably under load, and that deflection is now part of your measurement chain whether you accounted for it or not. Even the sensor itself stops being something you casually pick up: a compression cell rated for hundreds of thousands of pounds weighs several pounds and wants handling accordingly.
Traceability changes character too. Force is realised at the highest level by deadweight machines, which generate known force directly from calibrated masses and gravity rather than by comparison with another instrument. That gives an unbroken chain to SI units at very low uncertainty — but there is a finite supply of such machines in the world, and the largest of them, at the National Institute of Standards and Technology, generates one million pounds-force. Much of the world's high-force traceability ultimately runs through it. Once your sensor's capacity is measured in hundreds of thousands of pounds, calibration is no longer a routine errand; it is a service offered by a limited number of laboratories.
The sensor design responds to all this by getting stiffer, not bigger. Loading a column of precipitation-hardening stainless in pure axial compression uses the strongest path available in metal, and heat treatment of grades such as 17-4 PH multiplies strength several times over standard stainless without disturbing the dimensions of a precision part. That combination is how a compact cell absorbs hundreds of thousands of pounds while moving a thousandth of an inch. You find such sensors in structural and materials testing, geotechnical work, heavy machinery and crane verification, aerospace airframe testing, oil and gas equipment qualification, and offshore and marine structures.
Same physics as any load cell. Different things go wrong.
Getting the signal. The bridge needs energising — 10 VDC is standard. Load distorts the element, gauge resistances move, balance is lost, and a few thousandths of a volt appear at the output. Everything downstream is scaled by what you fed in, which is why the sensitivity figure carries volts on both sides of the slash. Amplify it, filter it, digitise it, apply the certificate, read force. Supply a different voltage than the certificate assumed and the entire scale moves with it.
Long cable runs stop being free. This is where high-force installations differ from bench work. Big test frames put distance between the sensor and the electronics, and copper has resistance. Send excitation down a long cable and some of your supply voltage is lost in the wire rather than reaching the bridge, so the sensor is quietly running at less than its rated excitation and reading proportionally low. The error grows with length. Four-wire cells simply suffer it; six-wire designs add sense conductors so the instrument can measure the voltage actually arriving at the bridge and compensate. If your run is long, this is a specification to settle before ordering rather than a problem to diagnose afterward.
Stiffness governs speed. Strike a sprung mass and it oscillates at a rate set by how readily it yields; permit only a single thousandth of an inch at full load and that rate lands in the tens of kilohertz. Trustworthy measurement occupies roughly the bottom fifth to tenth of it, which is generous room for brief events — assuming nothing downstream throws it away. Filtering in the conditioner and the sample rate of whatever records the signal both belong on the specification sheet next to the sensor.
The structure joins the measurement. At these forces the mounting surface and the pressing member are no longer passive. A plate that seemed rigid at a tenth of capacity will dish measurably at full load, redistributing force across the sensor and bending your calibration curve out of shape. Surfaces need to be hard, flat, and thick enough to stay that way loaded. A convex loading face helps by defining where contact occurs, but only against a mating surface flat enough to honour it.
And alignment is unforgiving. An axial design counts force travelling down its own axis; anything arriving at an angle is only partly counted. At two hundred tons a fractional angular error is an enormous absolute side force — large enough to matter to your data and, in a poorly designed fixture, to the hardware.
At the top of the capacity range, the unglamorous questions are the ones that decide whether an installation works. Walk us through the frame and the forces involved and we will tell you where the exposure sits — it is rarely where people expect.
Establish the real peak, then the overload margin. Not the nominal load, the worst credible one, including whatever a hydraulic system could deliver if a valve stuck or an operator mis-set a limit. Compare that against the safe overload rating, and design a mechanical stop into the frame. At these forces a runaway is not a bad afternoon, it's a hazard.
Settle calibration and traceability before you buy. Ask what standard your quality system requires, whether the certificate needs to be traceable, and which laboratory will actually do the work at your capacity. There are far fewer facilities able to apply several hundred thousand pounds than able to apply a few thousand, and lead times and cost reflect it. Building that into your schedule at specification time is much easier than discovering it when a recalibration falls due.
Design the load path as carefully as you choose the sensor. What presses down, how hard is it, how flat, and how reliably centred? What does the cell sit on, and does that surface stay flat at peak? Machined seats, hardened platens, and guided rams are not luxuries here — they are how you keep a large force arriving where the sensor expects it.
Decide the electrical route. How far is the sensor from the instrument, and does that distance warrant sense conductors to compensate for cable losses? Standard cable assemblies come in several lengths for exactly this reason; picking the right one at order time avoids a splice and an unknown error later.
Match the sensor to the event. A load that builds slowly and sits there asks little of anything. Impacts, drops, and cycling at frequency ask a great deal, and reward the least yielding design available — so long as the electronics behind it aren't quietly discarding the result. Give us the duration of the briefest thing you need to capture and we can reason back along the chain from there.
Then the practical remainder. Direction, since compression designs are certified pushing and tension is a separate exercise to specify. Environment, using the compensated band and drift coefficients to convert a temperature swing into a calculable error. And handling: a sensor weighing several pounds needs lifting into a fixture deliberately, not balanced hopefully on a platen.
And what reads it. At the simplest that is a regulated supply and nothing more. More often it is an amplifier signal conditioner module feeding acquisition equipment, or a digital display running alarms, analog output or logging on its own. Where cells rotate between frames, Cal-Teds plug and play keeps the calibration with the sensor — at 200 tons, a mistyped scale factor is not a small mistake.
Peak force, frame description, cable distance, and whatever your quality system demands — send us those four and we can specify this properly. Stocked capacities leave the following day, and teaching and research buyers qualify for academic rates.
CLC Series Load Cell Applications.
The Transducer Techniques CLC Series low-profile load column load cells, known for their high compression capacity, accurate load distribution, and ultra-fast frequency response, are versatile force measurement devices suitable for a range of applications.
- Structural Testing: The CLC Series load cells are widely employed in structural testing applications, where they measure the compression forces experienced by various structures and materials.
- Materials Testing: In materials testing laboratories, CLC Series load cells are used to perform compression tests on a variety of materials, including concrete, asphalt, steel, and composites.
- Geotechnical Engineering: Geotechnical engineers use CLC Series load cells to assess soil and rock properties. They apply compressive loads to soil and rock samples to measure their strength and deformation behavior.
- Heavy Machinery and Equipment Testing: The load cells are employed to test the performance and safety of heavy machinery and equipment, such as cranes, hoists, and hydraulic systems.
- Aerospace and Aircraft Testing: The aerospace industry utilizes CLC Series load cells for structural testing of aircraft components and materials.
- Automotive Testing: In the automotive sector, CLC Series load cells are used for testing vehicle components, including engines, suspensions, and chassis systems.
- Oil and Gas Industry: The load cells are applied in the oil and gas sector for various applications, such as testing drilling equipment, evaluating pipeline integrity, and assessing the performance of pressure vessels and storage tanks.
- Research and Development: Engineers and researchers use CLC Series load cells in R&D activities to conduct experiments related to structural analysis, materials testing, and product development.
- Custom Machinery and Equipment: Manufacturers and research facilities integrate CLC Series load cells into custom-built machinery and equipment designed for specialized testing and manufacturing processes.
- Offshore and Marine Applications: In the maritime industry, CLC Series load cells are used for testing offshore structures, mooring systems, and maritime equipment.
- Educational and Training Laboratories: Educational institutions incorporate CLC Series load cells into engineering and materials science laboratories to teach students about force measurement principles.
Their ability to handle high compression loads and provide fast frequency response makes them essential tools in industries and applications where accurate force measurement is critical for safety, quality, and performance assessment.
Frequently Asked Questions
What capacities does the CLC Series cover?
Five models: 50,000, 100,000, 200,000, 300,000, and 400,000 lb. That top figure is 200 tons, which puts the CLC at the very top of our compression range — where our other series finish, this one begins. Below 50,000 lb our column and load button families are the appropriate starting point.
How does the CLC hold 400,000 lb while deflecting only 0.001 inches?
By loading a column of heat-treated 17-4 PH stainless in pure axial compression, which is the strongest way to load metal. The material does the rest: 17-4 PH is a precipitation-hardening stainless whose heat treatment forms fine strengthening particles throughout the structure, multiplying its strength over standard grades without disturbing the dimensional precision the part depends on. One thousandth of an inch at full rated output is the lowest deflection figure across our entire line.
Why is the CLC's natural frequency 32,000 Hz on every capacity?
Because deflection is held constant at 0.001 inches throughout the series, and ringing frequency follows directly from stiffness. Where many product families see frequency vary with capacity, the CLC delivers the same 32,000 Hz whether you fit the 50,000 lb model or the 400,000 lb one. Practically, that means changing capacity mid-programme doesn't change your dynamic behaviour — useful when a test series spans several force ranges and you need results that stay comparable.
What can I actually measure with a 32,000 Hz natural frequency?
The working convention is that usable measurement bandwidth runs to about one-fifth to one-tenth of natural frequency, which puts the CLC in the low kilohertz range — comfortably enough to resolve impact events, drop tests, and rapid cyclic loading. The practical limit is usually elsewhere: a sensor this fast behind a heavily filtered conditioner or a slow acquisition system will give you the response of that slower element, not its own. Specify the readout chain with the sensor rather than after it.
What cable lengths are available for the CLC?
Mating cable assemblies are offered in 6, 12, 20, and 50 foot lengths. The range exists because high-force test frames routinely put real distance between the sensor and the instrument rack. Choose the length you need at order time rather than splicing later — and if you're going long, talk to us about the excitation arrangement, since cable resistance affects how much of your supply voltage actually reaches the bridge.
What threads and mounting does the CLC use?
Thread options are 1/4-28 and 3/8-24 depending on model. The loading diameter is slightly convex so force distributes predictably into the column rather than concentrating at whatever point happens to touch first. As with any axial compression design, that convex face needs to meet a flat, hard mating surface to do its job — the surface pressing down is effectively part of the measurement.
How much does a CLC load cell weigh?
From about 5 lb on the 50,000 lb model up to roughly 10 lb on the 400,000 lb model. Worth planning for: these are not sensors you casually position by hand while balancing a platen. Factor lifting and placement into your fixture design, and make sure whatever locates the cell can be engaged safely with something of that mass in your hands.
What accuracy does the CLC Series offer?
Nonlinearity and hysteresis are each 0.25% of rated output, nonrepeatability is 0.1% of rated output, and zero balance is 1.0% of rated output. Remember that these are percentages of rated output, so on a 400,000 lb cell they represent large absolute forces — which is the main argument for not over-specifying capacity. Choose the model your work actually needs rather than the largest one that will fit.
Is the CLC compression only, or can it be calibrated in tension?
It is a compression-only design and ships with compression calibration as standard, with optional tension calibration available. The column geometry and convex loading face are both built around force arriving downward along the axis. If tension is part of your application, specify the option at order time rather than assuming a compression certificate transfers — the load paths are genuinely different.
How does temperature affect a CLC reading?
The CLC is compensated from 60° to 160°F, with a safe operating range of −65° to 200°F. Within the compensated band, output drifts 0.005% of load per °F and zero drifts 0.01% of rated output per °F. Because both are published, a known temperature change becomes a calculable error rather than an unknown — and on a 400,000 lb cell, running that arithmetic before a long test is worth the two minutes it takes.
Questions From The Field
Who can actually calibrate a 400,000 lb load cell, and how is it traceable?
Fewer laboratories than you might expect, and it's worth understanding why. At the top of the chain, force is realised by deadweight machines that generate known force directly from calibrated masses and gravity, giving an unbroken link to SI units at very low uncertainty. The largest such machine in the world, at the National Institute of Standards and Technology, produces one million pounds-force — so a 400,000 lb cell sits at roughly 40% of the world's largest primary force standard. Practically, that means high-capacity calibration is a specialist service with real lead times. Confirm what your quality system requires and which laboratory will do the work before you need it, not when a recalibration falls due.
My CLC reads low and I'm running a 50-foot cable.
The cable is the first suspect. Copper has resistance, so over a long run some of your excitation voltage drops in the wire instead of reaching the bridge, and a sensor running below its rated excitation reads proportionally low — the effect grows with length. A four-wire connection has no way to detect this; a six-wire arrangement adds sense conductors so the instrument measures the voltage actually arriving at the bridge and corrects for the loss. Tell us your run length and instrument and we'll confirm what your setup needs.
My readings went non-linear at high force but were fine during low-load checks.
That signature points at the structure rather than the sensor. Everything is effectively rigid at a tenth of capacity; as force climbs, a platen or base that is too thin or inadequately supported begins to dish, the distribution of force across the loading face changes, and the relationship between applied load and reading stops being a straight line. Check the thickness, hardness, and support of both the mounting surface and the pressing member against your actual peak load, not a nominal figure.
How do I keep 200 tons centred on the loading face?
Engineer it rather than eyeball it. An axial column counts only the force travelling down its own axis, and at these magnitudes even a small angular error represents an enormous absolute side force — enough to corrupt data and, in a poorly designed frame, to endanger hardware. Use a machined seat that locates the cell positively, a guided ram or platen so the load lands in the same place each cycle, and a pressing face hardened, flat, and large enough to fully cover the loading diameter. Check alignment as part of commissioning rather than assuming it survived assembly.
What safety measures should I build into a 400,000 lb test setup?
A mechanical hard stop is the essential one — a hydraulic system with a stuck valve or a mis-set limit will exceed the 150% safe overload rating faster than anyone can intervene. Beyond that, treat the stored energy in a loaded frame as the primary hazard: keep people clear of the load path during application, use guarding where fragments could be thrown if a specimen fails, and approach a new fixture's expected load gradually the first time while watching the reading. The sensor is usually the cheapest thing in the room.
Should I buy a 400,000 lb CLC to cover everything, or size closer to my actual load?
Size closer. Accuracy figures are percentages of rated output, so a cell rated far above your working force spends its entire error budget on range you never use — 0.25% of 400,000 lb is 1,000 lb of potential error whether you're loading to 400,000 or 40,000. If your programme genuinely spans a wide range, two appropriately sized cells will usually give you better data than one oversized one, and the constant 32,000 Hz natural frequency across the series means their dynamic behaviour stays comparable.
Can I move a CLC between test frames, or should it stay installed?
Either works, but handle the practicalities. At 5 to 10 lb these are movable, though not one-handed while positioning a platen. If a cell rotates between frames regularly, machine each seat to locate it the same way so you aren't re-establishing alignment every time, and consider the OPT-TEDS option so calibration data travels with the sensor rather than depending on someone entering the right values at each station. Re-zero after every reinstallation as a matter of routine.
My CLC saw an overload. How do I tell whether it's still good?
Compare the unloaded zero against what it read when the cell was new — which is why recording that figure on receipt is worth the moment it takes. A zero that has shifted and won't return, or readings that no longer agree with a known reference load, indicate a genuine overload event rather than a transient. Safe overload is 150% of rated output, so brief excursions below that generally shouldn't cause harm, but at these capacities the consequences of guessing wrong are significant. Send it for recalibration rather than continuing on data you can't defend.