A digging bucket and a grading bucket look similar from the cab, but they answer opposite problems. The digging bucket concentrates machine force into a narrow cutting edge to break ground; the grading bucket spreads the same machine over a wide floor to finish it. Most excavator fleets carry one of each and swap them on the quick coupler several times a day.
The two KaiVoy ranges side by side
| Range | Widths | Coupler codes | Built for |
|---|---|---|---|
| SKD digging buckets | 430 – 800 mm (UT-430 to UT-800) | S30-180, S40, S45 | Opening trenches, breaking ground, loading |
| SKP grading buckets | 800 – 1400 mm | S30-180, S40, S45 | Slope finishing, backfill spreading, clean-up |
Coupler codes follow the attachment, not the machine – the same rule used across all KaiVoy excavator attachments. S30-180 covers compact carriers, S40 the 3.5 – 6 t class, S45 the 8 t class.
When to reach for which
- Digging bucket: the first pass into undisturbed ground, trenching to width, and any loading where the material has to be broken out before it can be moved.
- Grading bucket: everything after the spoil is loose – pulling the heap back, shaping batters, leaving a surface a compactor or a lawn can go straight onto.
- The overlap test: if the bucket has to penetrate the material to work, it is a digging job; if the material is already loose and only needs moving or levelling, the grading bucket does it in fewer passes.
How the widths pair up
A common pairing on compact machines is a 430 – 520 mm digging bucket with an 800 mm grading bucket: the narrow bucket sets the trench, the wide bucket clears the arisings. On 3.5 – 6 t machines the same logic runs from a 620 mm digging bucket to a 1200 – 1300 mm grading bucket. Full geometry for every model is on the product pages, and the attachment specifications page lists them in one table.
FAQ
Can a grading bucket dig?
Only already-loosened material. Its wide floor and lighter cutting edge are the wrong shape for penetration, and forcing it overheats the hydraulics for no progress.
Which one for backfilling a trench?
Grading bucket. If the trench is a cable trench, the cable laying bucket guide is sized exactly for the spoil-return passes.
How do I price a set?
Request a quote – Tell us the machine model and which coupler it runs, and we confirm the two codes and quote the pair together – nothing on this site is a fixed price.