Caring for your mechanical scales
Mechanical Scales
Both dial and steelyard mechanical scales work on a mechanical system of levers. At each contact point of the levers there is a knife and bearing joint to locate the levers accurately.
In dial scales the weight is transferred through a vertical connecting rod to the pointer, which is rotated through a rack and pinion. This is precisely the same way the steering on your car works, as does a mechanical clock.
In steelyard scales the connecting rod returns to knives/bearings and a lever to show the weight.
If your scale isn't working, then something is out of place, broken, loose or gone missing and these are these are the things you need to be aware of to help prevent this happening:
General use of mechanical scales:
* A violent movement, such as happens when the scale is hit or a heavy weight dropped onto the weighplate causes the plate to bounce, which in turn can cause both the knives and/or the rack and pinion to jump out of place. When this happens the scale will not zero or weigh correctly.
* A violent movement can cause a part to fall right off. Generally this happens when parts have loosened over time and use, and you would expect to find the part under the scale. Do not lose it! Some parts are now obsolete.
* Because the levers move with the weight applied they need a free area underneath, so any debris under the scale can inhibit the free movement of the scale and cause errors.
-sweeping under the scale from time to time is a good idea!
-avoid operating the scale on an uneven surface as this can cause the knives to shift.
Take care when shifting a scale from one location to another:
* Jarring or putting the scale down heavily when you move it to its new site can shift the knives so they no longer match up with the bearings. A sure sign of this is when the weighing plate rocks and is uneven.
* The levers can be broken when moving large scales with a fork hoist if the forks get caught under them rather than going right under the scale to span both sides.