Caster Selection Guide: Transformers, Steel Coils & Ship Blocks

A 10-Year Factory's 3-Minute Chart (Plus 3 Mistakes That Cost Buyers Thousands)

Three Questions We Get Every Week

1. "We're moving a 12-ton transformer — will your 6-inch wheel hold?"
2. "Steel coil edge-rides our dolly and the tread looks cracked after a month. Why?"
3. "Shipyard is 300 m from the sea. Normal galvanized is already flaking at 5 months."

These aren't casual questions — a wrong wheel here means a dropped load. So here's the chart we hand to customers before any quotation, stripped of sales talk.

The Chart (Screenshot-Worthy — Bookmark It)

Mistake #1: Quoting Single-Wheel Rating — Then Forgetting the 0.8 Rule

A buyer sends: "I need 500 kg per wheel, 4 wheels, done."

Real dynamic load isn't 4 × 500 = 2,000 kg. For manually pushed carts on real floors, we spec at ≈80% of the sum​ — shock at start/stop, one wheel hitting a bump, off-level parking. That 12-ton transformer move above? We didn't spec eight 1,500 kg wheels. We spec'd four A04 8″ rated 2,500 kg each​ — because four corners share load unevenly and a dragging fork is what tips a tall tank.

Rule we live by:​ size for the worst corner, not the average.

Mistake #2: Normal Galvanizing at the Shore

Shipyards, coastal prefab yards, cold-storage entrances with brine — standard electro-galv forks start white-rusting around month 4–6.

Our fix for A04 coastal orders: thick-coat hot-dip galvanizing​ (or 304 stainless fork on request). Cost up ~8–12%, service life more than doubled in our coastal pilot runs. One shipyard client swapped in Q3, checked at Q3+14 months: still bare metal at the weld lines.

If your site is within ~2 km of salt water — say so in the first email. It changes the fork spec, not just the price.

Mistake #3: "More Spring = Better Ride" (It Can Tip You Over)

Dual springs are brilliant on a low, wide die cart. On a tall, narrow transformer dolly with a high center of gravity, too much fork float turns every push into a pendulum. Operators lean into it, the cart swings, and you've invented a rollover risk to solve a vibration problem.

Our ordering logic for tall loads:

• Low & heavy + bumpy → max spring travel
• Tall & narrow + smooth → moderate spring, or rigid if under ~450 kg/wheel
• Anything over 1.5 m tall + over 3 T → we add a swivel-lock / side-pedal brake as standard, not optional

That side-pedal brake on the A04-1KU? It's not a upsell. On a 2-ton cabinet on a slight incline, it's the difference between "parked" and "incident report."

How a Real Inquiry Turns Into a Spec (Our 4 Steps)

1. You send​ — equipment weight, dimensions, photo of floor, travel distance, environment (heat / oil / salt / washdown)
2. We reply in 24 h​ — model + size + hardness + spring verdict + fork finish, no PDF fluff
3. Free sample + test report​ — we roll your actual load on your actual floor if you're within truck range; otherwise we issue load/impact/roll-test data against your stated weight
4. MOQ from 4 pcs​ — mix A04 + K01 + A05 in one order if your plant runs several lines

Brands we've already gone through this with: BYD · Chery · XPeng · SAIC-Volkswagen​ — mostly A04 8″ dual-spring and K01 6″ rigid on assembly-line dollies. When your plant manager asks "who else runs this on a live line?", that's the answer we point to.

FAQ — The Ones Our Engineers Answer Most

Q: Can one dolly mix 6″ in front and 8″ in back?

A: Common on 10+T transformer skids — larger rear wheels bridge rail gaps, fronts keep tracking. We draw it.

Q: PU tread cracking on steel coil — is it the hardness?

A: Usually edge-riding + oil. We go to a slightly tougher PU compound or add a steel-edge guard. Send the coil ID width.

Q: Do you do stainless forks for pharma/washdown?

A: Yes — 304 fork + sealed 6205 bearing, IP-grade. Longer lead time, quoted on request.

Q: Can I get the A04 brake with a foot-pedal instead of side-pedal?

A: Both, plus total-lock (wheel + swivel at once) on the 80-S-MKP-450 style triple-config. Specify at inquiry.