Abstract: A load cell comprises a block with a recess in an upper rectangular surface thereof. A plate overlies the upper surface and is parallel thereto and spaced therefrom by a spacer interconnecting the block and the plate at one end of the plate so the remainder of the plate can deform on application of a load to an upper surface thereof. The position of application can be adjusted along the length of the plate. Damage to the plate is avoided on application of an excessive load by its engagement with the upper surface of the block. The deformation of the plate is measured by an adjustable screw which projects downwardly from an undersurface thereof into the recess which contains a circuit board carrying an optical switch so that the screw gradually interrupts the transmission of light from a light emitting infrared diode to a photo transistor of the optical switch.