If you’ve been around job sites as long as I have, you know that sometimes the most effective tools aren't the prettiest. I recently put a 130kg (approx. 287 lbs) electric frog-style tamping rammer through its paces. While gasoline-powered rammers are common, these electric "frogs" are a staple for specific trench work and foundation backfilling where you want to avoid exhaust fumes or simplify your fuel logistics.
Power and Performance in the Trench
This unit runs on a 3kW motor wired for 380V, spinning at 1,450 RPM. When you engage the drive, this thing really moves. I clocked the forward speed at about 8–13 meters per minute (approx. 26–42 feet per minute).
What really matters, though, is the compaction force. With an impact energy of 300–600 N.m and a jump height of 200–230mm (approx. 8–9 inches), it packs a serious punch. It hits the ground between 140 and 150 times per minute. I tested it on standard loose soil backfill, and the density we achieved after a few passes was impressive for a machine of this footprint. The 120 x 550mm (approx. 4.7 x 21.6 inch) base plate is narrow enough to get into those tight runs but long enough to stay stable during the "hop."
Survival Guide: Maintenance is Non-Negotiable
Because this machine literally spends its entire life jumping up and down on dirt, it’s trying to shake itself apart. In my experience, if you don't stay on top of the bolts, you’re asking for a "rapid unscheduled disassembly."
Before you even plug it in, check these three things:
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Lube: Never, and I mean never, start the motor without checking the oil levels in the lubrication points.
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Fasteners: Walk around the machine with a wrench. Check every single bolt. If it's loose, torque it down.
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Electrical: Ensure the switches and cables are solid. Working with 380V on wet or loose soil means your insulation needs to be perfect.
Pro Tips from the Field
During my testing, I noticed a few quirks that will save you a headache (and money):
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Watch the Heat: Don't run this thing indefinitely. Keep an eye on the motor temp; if it’s getting hot to the touch, give it a breather.
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No Sharp Turns: Trying to force a sharp turn while it's jumping is a great way to snap a belt or tip it over.
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Know Your Ground: This is a dirt tool. If you try to use it on frozen ground, hard-pack rock, or soil filled with bricks and debris, you're going to break the base plate or burn out the motor. It also hates "split-grade" surfaces where one side is soft and the other is hard—that’s a recipe for a tip-over.
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Safety First: When you're done, don't just hit the "off" switch on the handle. Go to the main breaker and pull the plug.
The Bottom Line
For 130kg (287 lbs), this is a rugged, high-output compactor that’s perfect for contractors doing heavy trench work or foundation prep. Just remember to keep your B930 and B1800 belts tensioned, and it’ll treat you right.
