oncrete finishing is the stage of every floor project that decides whether the slab earns its keep. A surface that is not floated, compacted and troweled at the right moment will crack, dust or delaminate long before its design life is up — and on a large slab, how you finish it also decides how long the crew is out there. The QUM-78HA heavy-duty ride-on concrete power trowel from DYNAMIC, manufactured by Shanghai Jiezhou Engineering & Mechanism Co., Ltd., is designed for exactly this bottleneck: high-capacity, high-quality finishing on big pours, at a pace walk-behind machines cannot match.
Specifications
| Specification | QUM-78HA |
|---|---|
| Type | Ride-on concrete power trowel |
| Engine | Honda GX690, air-cooled, 4-stroke gasoline |
| Max output | 17.9 kW (24 HP) |
| Max engine speed | 3,600 rpm |
| Rotor speed | 160 rpm |
| Rotor configuration | Twin discs, 36 in / 1 m each |
| Working dimension | 1,910 × 915 mm |
| Fuel tank capacity | 40 L |
| Machine weight | 409 kg |
| Overall dimensions (L×W×H) | 2020 × 1,015 × 1,240 mm |
| Steering | Hydraulic, twin-lever |
| Warranty | 1 year on core components |
A power trowel works by spinning blades that ride on the surface of freshly placed concrete — first floating the slab flat and compacting its surface, then, as the concrete sets, burnishing it to a hard, smooth finish. The larger and heavier the machine, the more consistent the pressure it applies. That is the logic behind the ride-on design: put the operator's weight and a big engine directly above the blades, and the finish quality of a large slab no longer depends on the endurance of one person walking behind a small machine.
Honda GX690 Power You Can Rely On
At the heart of the QUM-78HA is a Honda GX690 air-cooled, four-stroke gasoline engine that delivers up to 17.9 kW (24 HP) at a maximum engine speed of 3,600 rpm. Honda GX-series industrial engines are the workhorse of construction equipment worldwide — simple, easy to start, economical to run and backed by a global parts network. On the trowel, that power translates into the two things a finishing crew needs most: enough blade speed to keep working as the concrete sets, and enough torque to drive the machine across a wet slab without stalling. The rotors turn at up to 160 rpm, a speed range that lets operators move smoothly from the floating stage to the final burnished finish without changing machines.
Twin Rotors for Maximum Coverage
The QUM-78HA carries twin rotors, each fitted with a 36-inch (approximately one meter) blade assembly, giving a total working coverage of about 1,910 × 915 mm per pass. The twin-rotor layout is the key to ride-on performance: it doubles the blade coverage of a single-rotor machine and, because the rotors counter-rotate, it cancels the lateral drift that makes single-rotor trowels tiring to control. The result is a machine that stays stable, tracks straight and finishes a wide band of concrete with every pass, cutting the number of passes across a big floor dramatically.
Hydraulic Control and Operator Comfort
Operator control is where ride-on trowels stand or fall, and the QUM-78HA uses hydraulic steering with twin control levers. The hydraulic system delivers smooth, progressive steering response instead of the jerky corrections typical of mechanical linkages, so the operator can hold a precise line along edges and around columns. With the operator seated directly above the slab, body weight adds to the downward pressure on the blades, improving blade contact and surface density on every pass. For long shifts, comfort matters as much as control: a seated operator stays productive far longer than one pushing a walk-behind unit, and the dual-lever layout keeps both hands where they need to be with minimal effort.
Built for a Hard Working Life
Finishing machines live a hard life, and the QUM-78HA is built accordingly. A heavy-duty gearbox rated for continuous load is designed to run without high-temperature oil leakage even during long finishing sessions, while an efficient transmission system keeps power delivery stable and reliable. The reinforced frame carries the weight of the engine and operator without flexing, and routine maintenance points are positioned for quick access. The machine ships fully assembled — fill the 15-liter fuel tank, check the oil, and it is ready to work.
Finish Quality: Flat, Dense, Ready to Seal
The point of a heavy trowel is not speed alone — it is the surface you are left with. As the blades pass over the slab, they compact the cream at the surface and close the small pores that would otherwise absorb sealer or turn into dust. The QUM-78HA's rotor speed and blade pitch can be set to suit the condition of the concrete, and the extra weight of the machine and rider presses each pass firmly into the surface. The payoff is a floor that is flatter, denser and more consistent — the kind of substrate that accepts densifiers, hardeners and sealers evenly and stands up to forklift traffic for decades.
Fixed Transport Wheels: A Detail That Saves Hours
One detail that sets the QUM-78HA apart is its fixed transport wheels. Ride-on trowels are heavy machines — the QUM-78HA weighs 365 kg — and moving them around site and changing blades has traditionally been awkward. The built-in wheels let one or two workers roll the machine from truck to slab without a forklift or crane, and they make blade and disc changes significantly more convenient. The result is less downtime between jobs and less manpower spent on logistics.
Productivity: Why Contractors Move Up to Ride-On
The productivity argument is simple arithmetic. A walk-behind trowel finishes a narrow band and demands constant walking; a ride-on machine such as the QUM-78HA covers roughly twice the width per pass while the operator rides. On a 5,000-square-meter warehouse floor, the difference is measured in days, not hours — and finishing speed matters because concrete only has a finite window in which it can be troweled properly. Once that window closes, the surface is what it is. With 24 HP on tap and a 1,910 mm working width, the QUM-78HA keeps large pours finishable from the first float to the final polish.
Applications
The QUM-78HA is built for large-area, high-quality concrete floors. Typical applications include warehouses and distribution centers, factory and workshop floors, shopping centers and retail spaces, parking structures and ramps, airport terminals and hangars, sports halls and arenas, and large residential or commercial slabs where flatness and durability matter. It handles both the floating stage (with float pans) and the final finishing pass (with trowel blades), and its hydraulic control keeps it manageable in confined areas despite its size. Contractors who pour big slabs, and floor contractors who demand a hard, flat, sealed surface, are the machine's natural customers.
Support and Customization
Backing the machine is DYNAMIC's one-year warranty on core components, after-sales service and OEM/ODM customization. Honda engine parts are available worldwide, and the manufacturer, Shanghai Jiezhou Engineering & Mechanism Co., Ltd., supplies both standard models and customized versions for fleet buyers. CE certification is available, which makes the QUM-78HA straightforward to bring into European and other regulated markets.
Conclusion
For any contractor whose schedule is governed by large concrete pours, the QUM-78HA ride-on power trowel is a straightforward business decision: more coverage per pass, faster finishing, better surface quality and an operator who is still fresh after a full day. Powered by the dependable Honda GX690, controlled hydraulically and built around a heavy-duty drivetrain, it turns the most labor-intensive stage of floor construction into the most productive one. If you are finishing big slabs and still doing it with walk-behind machines, it is time to look at what riding can do for your next project.
Post time: Sep-16-2026