Bucket capacity is rated by using heaped capacity and struck capacity. At present, heaped capacity is widely used.
1. Struck capacity
Struck capacity is defined as the volume bounded by the inside bucket contour without consideration for material supported or carried by spill guard or on bucket teeth.
2. Heaped capacity
Heaped capacity is defined as the volume in the bucket under the strike off plane, plus that of the heaped material above the strike off plane with an angle of repose of 1:2, without consideration for material supported or carried by the spill guard or bucket teeth.At present, there are different standards to define the heaped capacity of a hoe bucket, causing confusion. This is chiefly attributed to the difference in defining the angle of repose. On the contrary, for a loading shovel bucket, almost the same definitions are employed.
The angles of repose are shown in the following table :
From this table, we can see that Hitachi rating (based on JIS) and ISO use the same angle of repose. PCSA and SAE use the greater angle of repose.
JIS: Japanese Industrial Standards (A3403-4)
PCSA: Power Crane and Shovel Association (USA)
SAE: Society of Automobile Engineers (USA) (J296)
CECE: Committee for European Construction Equipment
ISO: International Standards Management (7451)
Sumber : Hitachi Excavator Handbook