Steelyard balance with rotatable cursor on balance arm - minimises wear and allows knife edge into arm notch

摘要

The design improves on two deficiencies inherent in conventional balances, such as erratic, jarring movement of the cursor between notches (4) necessitating support of the cursor's weight and causing wear of the knife edge (18) and notches is eliminated and uncertainties in judgement of the balanced condition are minimised. The balance arms (3, 7) are of circular section and the cursor bore is of slightly larger diamter. This arrangement permits the rotation of the cursor (5) around the bar and allows it to be slid along. The knife edge can thus be rotated into the appropriate notch (nearest the balance condition). The balanced condition is indicated by the coincidence of the plane of a horizontal plate (31) attached to the bars and a fixed circular stube end (30).