MNM Scales 250 lb Tension/Compression Load Cell Guide: 0.02 lb Accuracy & Peak Hold
- pete8781
- Jul 29
- 4 min read
Need more details or help choosing a fixture or application? Call MNM Scales at (832) 290-3120 or email mnmscales@yahoo.com.
The MNM Scales 250 lb tension/compression load cell system is a calibrated 250 lb x 0.02 lb S-type force-measurement package designed for users who need much finer force visibility than a typical high-capacity crane scale. The system combines an alloy-steel S-type load cell, digital indicator, rechargeable battery and power supply, two eye bolts, Peak Hold and RS232 output. Because the S-beam measures both tension and compression, it can serve as a portable hanging-force system or become the sensing element in a spring tester, cable-tension fixture, actuator test stand, small winch test, component pull fixture or production quality-control station.
250 lb Capacity With 0.02 lb Display Resolution
The headline specification is 250 lb capacity with 0.02 lb displayed increments. That equals 12,500 display divisions across the nominal range, allowing the operator to see small changes that would disappear on a 0.1 lb, 0.5 lb or 1 lb display. This is particularly useful when comparing springs, cables, actuators, clamping mechanisms or repeated production assemblies. Display resolution is not the same as total measurement uncertainty, however. Fixture alignment, sensor calibration, temperature, cable condition and side loading still matter when a process needs traceable or tightly controlled measurements.
What the System Includes
MNM lists the package as calibrated and ready to use out of the box. It includes an alloy-steel S-type load cell, a digital LED indicator with built-in rechargeable battery and power supply, and two eye bolts. The indicator uses a plastic enclosure with mounting bracket/hardware and supports desk, wall or column mounting at an adjustable angle. The display is listed as six digits, approximately 1 inch high, with backlight. The rechargeable battery is specified at 6 V.
Indicator Functions and Electronics
The indicator provides Zero, Gross, Net, accumulation, printing, counting, check weighing and Auto Hold, with lb/kg selection and RS232 output. MNM also highlights Peak Hold for the 250 lb system. The indicator is specified at 6000e, with a maximum of 30,000d and input resolution of 0.3 microvolt per division. It can drive up to eight 350-ohm load cells, although this package is calibrated around the supplied S-type sensor. Gravity adjustment is available for geographic compensation when a calibrated weighing system is moved to a location with materially different local gravity.
How the S-Type Sensor Works
S-beam sensors use bonded strain gauges arranged as a bridge circuit. When axial force stretches or compresses the sensing body, the strain gauges change resistance and produce a small electrical output proportional to force. The digital indicator supplies excitation and converts that signal into the calibrated reading. The threaded load points make S-beams naturally suited to inline testing. Industry application references use S-beams for spring testing, wire-tension measurement, linear test stands, material-test machines and dynamometers because they can measure force in both directions while fitting directly into the mechanical load path.
Peak Hold: One of the Most Useful Features for Force Testing
Many tests are decided by a momentary maximum rather than a stable force. A spring may reach its target force at a defined extension, a cable may experience a short tension peak, an actuator may produce maximum thrust at stall, and a pull test may have a higher breakaway force than its steady value. Peak Hold retains that maximum so the operator can read it after the event. For repeated tests, clear the held value between samples and keep the same fixture geometry and loading method.
Applications: Detailed Guides by Use Case
Cable, spring and small-component force testing — ideal when the 0.02 lb display helps distinguish small changes in spring force, cable tension, assembly pull strength or component compression.
Winch, actuator and motor pull-force testing — targets small electric winches, linear actuators, motors, solenoids and powered mechanisms that need measured thrust or pull rather than estimated output.
Fixture Design and Alignment
Accuracy begins with mechanics. Apply force through the S-beam’s primary axis and avoid twisting, bending and side loads. Clevises, rod ends or aligned eye hardware allow the sensor to follow the load instead of resisting an offset fixture. For compression work, use a structure that keeps the load centered and prevents buckling. For tension work, ensure every connector, grip and anchor is rated above the maximum intended force. A stiff, repeatable fixture is especially important when the goal is to compare differences of only a few hundredths or tenths of a pound.
Using RS232 for Test Records
RS232 gives the system a path into a compatible computer, printer or data-logging workflow. For production quality control, a recorded value can be associated with a serial number or lot. For R&D, a computer can simplify repeated sample logging. The interface alone does not define the software workflow, so match communication settings, cable pinout and receiving software before building automated records around it.
Troubleshooting Tips
If zero drifts, remove mechanical preload and let the system stabilize thermally before assuming an electronic fault. If the value changes when a fitting is moved sideways, inspect alignment and side load. If readings jump, inspect the cable, connector and fixture vibration. If a test is repeatable mechanically but the value has shifted after an overload or impact, perform a calibration check. If battery operation becomes erratic, charge the 6 V rechargeable battery fully and test again on AC power to separate power issues from sensor issues.
Frequently Asked Questions
Can it measure both pulling and pushing force?
Yes. The supplied S-type load cell is designed for tension and compression measurement in an appropriate fixture.
What does 0.02 lb resolution mean?
The display changes in 0.02 lb increments across the configured 250 lb range. Total process accuracy also depends on calibration and mechanical installation.
Is it portable?
Yes. The rechargeable indicator and separate sensor allow portable use, while the bracket also supports permanent desk, wall or column mounting.
Can it capture maximum force?
Yes. Peak Hold is useful for maximum pull, breakaway force and other short-duration peaks.
Technical Documents & References
A model-specific indicator PDF is not currently published on the MNM listing; this article therefore uses only functions and electrical specifications stated for the supplied system rather than assuming a manual from a different indicator model.
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