PART XIIPLATFORM WEIGHING MACHINES AND WEIGHBRIDGES
Materials and principles of construction
110.—(1) The steelyard indicator of a platform weighing machine or weighbridge shall not incorporate any readily removable parts, except the support for the counterpoises.
(2) There shall be a stop or stops to prevent any sliding poise from travelling behind the zero mark.
(3) The indicating mechanism may be confined in a locked box or case, provided that the indications or graduations are clearly visible.
111. The minimum movement from the horizontal of the steelyard indicator shall be as follows:—
(a)in the case of platform weighing machines—
(i)if they are of the vibrating weighing instrument type, three-eights of an inch in both directions;
(ii)if they are of the accelerating weighing instrument type, fiveeighths of an inch in one direction only;
(b)in the case of weighbridges—
(i)if they are of the vibrating weighing instrument type, half an inch in both directions;
(ii)if they are of the accelerating weighing instrument type, threequarters of an inch in one direction only.
112. If a movable hutch, barrow, frame or bucket is used instead of an ordinary platform on platform weighing machines and weighbridges, it shall form an essential part of the instrument without which the instrument cannot be balanced.
113.—(1) Loose counterpoises for platform weighing machines and weighbridges shall be identified with the instrument to which they relate by a number or other sufficient mark of identification, which shall be indelible. They shall also be marked with the weight which they represent; for example:—
“=1 cwt”.
(2) Loose counterpoises which are marked in units in the imperial system shall not be of hexagonal shape.
114. In the case of small portable platform weighing machines for use in the weighing of coal and commonly known as bob-up weighing machines, the counterpoises shall not be threaded on to a pin rigidly attached to one end of the main lever, but shall either be used in a tray or pan suspended from a knife-edge bearing or be placed on a loose shackle.
115. The balancing arrangement for platform weighing machines and weightbridges to compensate for daily wear and tear shall have a range not exceeding one-half per cent. of the capacity of the instrument and not less than one-eighth per cent. in each direction, and it shall be securely attached to the instrument and actuated by a detachable key.
116. In the case of platform weighing machines and weighbridges which are fitted with dials—
(a)all racks and pinions shall be made of hard metal;
(b)the extremity of the pointer shall not be a greater distance than three sixteenths of an inch from the dial, and shall meet but not obscure the graduations;
(c)the indicating mechanism and any cylinders or tanks containing liquid shall be protected from dust and from excessive variations of temperature;
(d)if the instrument is of a type commonly known as a self-indicating pitbank weighing machine, the pendulous lever, suspension rod and water box shall be suitably enclosed.
117. Platform weighing machines and weighbridges for use in weighing in units of both the imperial system and the metric system shall bear a clear inscription to that effect.
Testing
118. Platform weighing machines which are to be permanently fixed in the position in which they are to be used and weighbridges shall be tested, passed as fit for use for trade and stamped only when completely erected ready for use and installed at the place where they are to be used.
119. In testing platform weighing machines and weighbridges, the inspector shall where practicable—
(a)test the instrument at each numbered graduation up to and includin 1 ton, or such smaller amount as the last graduation on the steelyard indicator or dial may show; and
(b)test all loose counterpoises, if any, relating to the instrument; and
(c)either test the instrument ton by ton, or load it with heavy material to within 1 ton of its capacity and ascertain that an additional ton is correctly indicated to within the prescribed limits of error.
120.—(1) In testing platform weighing machines fitted with relieving gear, the inspector shall satisfy himself that—
(a)the machine falls within the prescribed limits of error when it is put steadily out of and into gear;
(b)the plate or platform is entirely disengaged from its bearings when the machine is in relief.
(2) Platform weighing machines and weighbridges shall indicate the same weight within half the prescribed limits of error when a load equal to one-quarter (or as near thereto as is practicable) of the capacity of the instrument is placed successively in the centre and near each end or corner of the platform.
(3) Platform weighing machines and weighbridges shall also fall within the prescribed limits of error when a load equal to the capacity of the machine (or as near thereto as is practicable) is uniformly distributed over the platform.
121. Schedule 2 hereto shall have effect for prescribing limits of error—
(a)in the case of Part I and VII, in relation to platform weighing machines (other than self-indicating pit-bank weighing machines);
(b)in the case of Parts I and VIII, in relation to self-indicating pit-bank weighing machines;
(c)in the case of Parts I and IX, in relation to weighbridges.
Stamping
122.—(1) On platform weighing machines and weighbridges fitted with dials, the stamp shall be placed on the plug or stud provided for that purpose on the housing of the instrument.
(2) On platform weighing machines and weighbridges not fitted with dials, the stamp shall be placed on the said plug or stud in a conspicuous position either on the shoulder or on the opposite end of the steelyard indicator.
123. Loose counterpoises for platform weighing machines and weighbridges shall not be stamped.