Cost of ownership

A copy pump is cheaper once. A genuine pump is cheaper twice.

Five years of ownership, measured on the same 20-tonne machine: purchase price, rebuilds, contamination damage and downtime. The numbers below come from a comparison sheet we keep for price arguments, with its sources listed at the end.

Five-year total

CopyGenuine

Purchase price¥4,500 – 8,000¥25,000 – 35,000

Design life1,680 – 5,000 h8,000 – 10,000 h

Real life, heavy duty8 – 14 months4 – 5 years

Purchases in five years4 – 51

Five-year total¥93,000 – 170,000¥34,000 – 50,000

Pressure at 1,680 h180 bar, then failure320 bar, still holding

Volumetric efficiency after 5,000 h< 80 %, falling> 92 %, steady

Four parts decide it

Swash plate

Genuine

High-chrome steel, carburised, 0.18–0.22 mm layer

Copy

Low-carbon steel, 0.04–0.06 mm plating

What it does

A quarter of the layer: it wears through, then scores the pistons

Piston shoes

Genuine

Bonded molybdenum, HRC 62+, sphere ±0.005 mm

Copy

Bare steel, under HRC 62, sphere ±0.02 mm

What it does

Four times the tolerance and no friction layer: internal leak rises 30 %+

Cylinder block face

Genuine

Ground to 0.003 mm flatness, ductile iron

Copy

0.028 mm waviness, ordinary cast iron

What it does

Nine times the waviness: the seal never closes

Valve plate

Genuine

Bronze, lapped, 8,200 h still in service

Copy

Brass, scratched within 400 h, dead at 1,680 h

What it does

A fifth of the life, and the debris goes into the whole circuit

How a copy pump dies

300 – 500 h

Oil film fails

Cold machine is quick, hot machine is slow. Ground clearance opens; hot oil leaks past. Cut the filter open: copper powder means shoes, silver means block and pistons.

¥2,000 – 4,000

500 – 1,000 h

Pitting and noise

The growl turns into a buzz, then into a rhythmic knock. Buzz is a sticking piston; knock is a broken shoe or a scored face.

¥3,000 – 6,000

1,000 – 1,680 h

The pump takes the machine down

Shaft breaks or the block bursts. Metal is already circulating: valve block ¥8,000–15,000, cylinders ¥5,000–10,000 each, flush and oil ¥2,000–5,000, downtime ¥10,000–15,000 a day.

¥4,500 – 8,000, every 5–7 months

What to ask before you buy any pump

Ask for the plate: full TYPE code, not just K3V112.
Ask which valve plate material: bronze or brass.
Ask for the shaft and regulator variant in writing.
Ask what happens to the system when it fails: is the debris path blocked or not.

Comparison sheet compiled 2026-08-19 from six sources, including a teardown audited by SGS and market service-cost data. Figures are ranges, not quotations; ask for the sheet.