Single point and shear beam cells overlap in capacity but solve different mechanical problems. Choosing by capacity alone is why so many platform scales end up with corner errors that no calibration can fix.
Single point cells
A single point cell is designed so that a load applied anywhere on the platform produces the same output. That property is what allows a platform to be supported by one cell at its centre, with the platform bolted directly to the cell. Off-centre compensation is built into the element geometry, and it holds only within the specified platform size and only when the cell is mounted flat. Typical capacities run from 3 kg to 500 kg.
Shear beam cells
A shear beam measures shear strain in a web, which is insensitive to where along the beam the load is applied but not to load offset across the beam. Platforms therefore need four cells, one at each corner, summed in a junction box with corner adjustment. Shear beams are shorter, stiffer and available in much higher capacities, and they tolerate side loads better than single point cells.
Decision rule
One cell and a small platform: single point. Four corners, a large deck, or repeated side loads: shear beam. If the platform is longer than about 600 mm in either direction, four shear beams with corner trimming will be more stable than one large single point cell, whatever the datasheet says about off-centre compensation.
Kevin Huang