Picking the right reversible plate compactor is about matching centrifugal force, operating weight, baseplate size, and engine power to the soil type, lift thickness, trench/area dimensions, productivity targets, and site constraints. This guide shows :
- You need the critical specs that directly affect compaction in practice.
- A step-by-step sizing method with a worked example.
- Reference tables mapping soil types → force ranges → lift thickness.
- Productivity, fuel, and ROI calculators for bids and rentals.
- What “power” really means (and how much you actually need).
What “right size” Really Means
Reversible plate compactors fill the gap between forward plates and small rollers. They deliver high compaction energy with bidirectional travel, letting operators compact in tight spaces and trenches without turning the machine. “Right size” means a model that:
- Achieves target density (Proctor/modified Proctor or plate load objectives) for your soil type and lift thickness.
- Fits the geometry (trench width, slab edges, around structures) and site logistics (ramps, crane picks, doorways).
- Meets productivity targets (m²/hr or linear meters/hr).
- Balances engine power, weight, and plate area for efficient energy transfer—not just high paper specs.
The Specs that Matter
Centrifugal force (kN)
Primary driver of compaction energy—the dynamic force generated by the exciter(s). More isn’t always better; too much force in thin lifts or on granular surfaces can cause over-vibration, particle migration, or surface heave.
Operating weight (kg)
Mass helps transmit force and reduce recoil. Heavier plates generally compact deeper lifts, but weight must be balanced with maneuverability and surface bearing limits.
Baseplate size (W×L, mm)
Determines contact pressure and footprint stability. Larger plates spread force over a bigger area (better surface finish, fewer “waves”), but lower contact pressure if force doesn’t scale with area.
Vibration frequency (Hz / vpm) and amplitude (mm)
Higher frequency generally benefits granular soils, while higher amplitude helps cohesive or mixed soils. Reversible plates typically run 55–70 Hz (3,300–4,200 vpm) with 1.2–2.2 mm amplitude depending on the class.
Engine power (kW/HP)
Power must be sufficient to drive the exciter at load. Once the exciter requirement is met, extra horsepower adds little unless you increase force or speed. Over-spec’d engines usually waste fuel.
Travel speed and gradeability
Affects cycle time, especially on long passes and ramps. Typical 35–28 m/min forward and low teens m/min reverse for mid/heavy classes.
Model Classes and Typical Specs
| Class | Typical Force (kN) | Operating Weight (kg) | Baseplate (mm) | Frequency (Hz) | Typical Engine (kW) | Use Case Highlights |
| Light Reversible | 20–30 | 80–140 | 400–500 × 650–700 | 60–70 | 3.5–4.5 | Pavers, narrow trenches, granular sands with thin lifts |
| Medium Reversible | 35–45 | 160–250 | 500–600 × 700–800 | 55–65 | 4.8–6.5 | General civil works, base course, utilities |
| Heavy Reversible | 50–65 | 300–420 | 600–700 × 800–900 | 55–65 | 6.5–8.5 | Thick lifts, backfill, stabilization layers |
| Extra-Heavy Reversible | 70–90+ | 450–600+ | 700–850 × 900–1,000 | 55–60 | 8.5–11+ | Large excavations, subbase deep compaction, rental fleets for broad demand |
Soil Type, Lift Thickness, and Force Selection
Lift thickness (the layer compacted in one pass) depends on soil gradation and moisture. Use the table below as a starting point for typical well-managed moisture conditions (near optimum):
Soil type vs recommended force & lift
| Soil Type (Unified/General) | Example Materials | Recommended Force (kN) | Typical Lift (mm) | Frequency Bias | Notes |
| Clean granular (GW, SW) | Crushed rock, well-graded sand | 35–55 | 200–350 | Higher freq | Very responsive; avoid over-vibration causing particle migration |
| Granular with fines (GP-GM, SP-SM) | Road base with fines | 45–70 | 200–300 | Mid freq | Balance amplitude and frequency; watch moisture window |
| Silty sand/gravel (SM, GM) | Moist granular mixes | 45–65 | 150–250 | Mid freq | Sensitive to water content; verify with field test |
| Lean clay / clayey sand (CL, SC) | Cohesive or mixed | 50–80 | 150–220 | Lower freq, higher amp | Requires energy + controlled passes to avoid pumping |
| High plasticity clay (CH) | Fat clays | 65–90+ | 120–180 | Lower freq, higher amp | Often inefficient with plates; consider sheepsfoot/roller if persistent |
The sizing method (five steps)
You can turn this into a quick worksheet for your sales team.
Step 1 — Define the job
- Soil type and moisture window
- Lift thickness target (mm)
- Geometry (trench width, area size, clearance)
- Productivity (m²/hr or linear m/hr)
- Access/handling constraints (ramps, crane, vehicle limits)
Step 2 — Choose a force band
Use the Soil vs Force table above to pick a kN band aligned with your lift thickness and soil.
Step 3 — Match weight and baseplate
- Thin lifts + granular → moderate weight, higher frequency, adequate plate area.
- Thick lifts + cohesive/mixed → heavier mass, higher amplitude, larger baseplate for stability.
Step 4 — Check engine power (sanity check)
Ensure rated engine output supports selected force at working frequency with 10–15% margin. (Most reputable models are balanced; beware of very high kN on small engines.)
Step 5 — Validate with productivity & geometry
- Plate width should fit trench with 50–100 mm clearance either side.
- Compute passes, travel speed, and area output to confirm schedule.
- Plan for reversals (reversible plates shine in trench confines).
Worked Example: Utility Trench Backfill
Scenario
- Soil: well-graded sand with fines (SP-SM)
- Target lift: 220 mm
- Trench: 700 mm internal width, long runs
- Daily target: 1,800 m linear trench (single lift)
- Access via site ramps up to 20% grade
Step 1–2: Force band
SP-SM at 220 mm lift → 45–65 kN recommended.
Step 3: Weight & plate
Pick Heavy Reversible (~50–60 kN, 300–380 kg, 600–700 mm wide plate). Plate width ~600–650 mm leaves ~25–50 mm per side—ideal.
Step 4: Engine sanity
A 7–8 kW engine is typical here; adequate for ~55 kN plates.
Step 5: Productivity
Assume effective forward speed 30 m/min and reverse 12 m/min with reversing every 10 m.
- Net cycle speed (allowing reversals & overlaps): ~22–24 m/min
- Pass width: 0.62 m effective
- Linear productivity: ~1,300–1,450 m/hr per pass (theoretical).
- Accounting for staging, checks, and lift management, use 30–35% efficiency factor:
~450 m/hr realistic → 4 hrs for 1,800 m (single lift) with one machine and an experienced operator.
Productivity Planning Tables
Area productivity (rule-of-thumb)
Use this to sanity-check bids.
| Model Class | Effective Plate Width (m) | Typical Net Speed (m/min) | Planning Efficiency* | Practical m²/hr |
| Light | 0.45 | 28 | 0.30 | ~380 |
| Medium | 0.55 | 26 | 0.35 | ~500 |
| Heavy | 0.65 | 24 | 0.40 | ~620 |
| Extra-Heavy | 0.75 | 22 | 0.40 | ~660 |
Linear productivity (trenches)
| Model Class | Effective Width (m) | Net Speed (m/min) | Efficiency | Practical m/hr |
| Light | 0.40 | 30 | 0.30 | ~360 |
| Medium | 0.50 | 28 | 0.35 | ~590 |
| Heavy | 0.62 | 24 | 0.40 | ~595 |
| Extra-Heavy | 0.72 | 20 | 0.40 | ~575 |
Matching Force, Weight, Frequency, and Amplitude
Recommended envelopes by application
| Application | Preferred Force (kN) | Weight (kg) | Frequency (Hz) | Amplitude (mm) | Notes |
| Pavers & patios | 20–30 | 90–140 | 60–70 | 1.2–1.6 | Avoid scuffing; use pad kits |
| Road base granular | 45–65 | 200–420 | 55–65 | 1.6–2.0 | General civil, fast production |
| Mixed soils (SM/SC) | 50–80 | 300–500 | 55–60 | 1.8–2.2 | Balance amplitude & frequency |
| Cohesive backfill | 65–90 | 400–600 | 55–60 | 1.8–2.2 | Watch moisture; reduce lift if pumping |
Engine Power: How Much is “enough”?
Exciters convert engine power into vibration. Most mid/heavy reversible plates do not operate power-limited; they are force-limited by exciter design. A practical sanity check:
- Light (20–30 kN): 3.5–4.5 kW
- Medium (35–45 kN): 4.8–6.5 kW
- Heavy (50–65 kN): 6.5–8.5 kW
- Extra-Heavy (70–90 kN): 8.5–11+ kW
Going far above these bands does not improve density unless your plate/exciter and mass are also scaled. Prioritize reliability, fuel curve, and service network over raw horsepower bragging rights.
Baseplate Geometry and Surface Finish
- Longer plates help flatten the surface (fewer ripples), especially on granular base courses.
- Wider plates reduce passes on large areas, but verify contact pressure remains adequate (kN per cm²).
- Edge radius and steel grade influence glide and wear. Induction-hardened or abrasion-resistant steels extend life on crushed aggregates.
Practical Constraints that Change Your Pick
| Constraint | Impact | Sizing Guidance |
| Trench only 600–650 mm wide | Caps plate width | Consider 450–600 mm plate; keep 25–50 mm clearance per side |
| Frequent ramps (15–20%) | Needs torque and traction | Favor heavier class with robust reverse torque; check gradeability |
| Compaction near structures | Vibration limits | Use lower amplitude / rubber buffers; more passes instead of higher force |
| Crane/vehicle limit 350 kg | Weight cap | Top-end medium or light-heavy hybrid |
| Noise/vibration limits | Community rules | Select lower frequency or enclosed engine; schedule working windows |
Fuel, Cost, and ROI Planning
Fuel consumption estimator
A quick planning tool (typical modern engines):
| Class | Engine (kW) | Load Factor (avg) | Fuel Use (L/hr, gasoline) | Fuel Use (L/hr, diesel) |
| Light | 4.0 | 0.55 | ~1.1 | ~0.9 |
| Medium | 6.0 | 0.60 | ~1.6 | ~1.3 |
| Heavy | 8.0 | 0.65 | ~2.1 | ~1.7 |
| Extra-Heavy | 10.0 | 0.70 | ~2.7 | ~2.2 |
Ownership vs rental rough cut
| Parameter | Light | Medium | Heavy |
| Typical Purchase (USD) | 2,800–4,200 | 4,500–7,800 | 7,500–12,500 |
| Typical Day Rate (USD) | 60–85 | 85–120 | 120–180 |
| Break-Even Days (≈) | 45–55 | 50–75 | 60–85 |
If you run >80 rental-equivalent days/year, ownership makes economic sense—assuming you have storage and maintenance capability.
Field Verification Protocol (keep it simple)
Set moisture within OMC ±2%.
Trial strip: compact a 5 m × plate-width section at your planned passes.
Measure density (nuclear gauge or sand cone) or plate load if required.
If below target:
- Increase passes; if still low, reduce lift or step up force class.
- Check for over-wet or over-dry; adjust moisture.
Document settings (passes, speed, moisture) and repeat per change in soil/lift.
Safety and Ergonomics Still Matter
Hand-arm vibration (HAV) control via isolated handles saves operators on long shifts.
Reversing response should be smooth and predictable (hydraulic/mechanical control quality matters).
Guarding & tie-downs for transport; dead-man controls where required by local regulation.
Provide hearing protection guidance; reversible plates in confined spaces can exceed safe dBA.
Putting it All Together—Decision Matrix
Use this matrix to jump to a model class quickly, then fine-tune with the previous sections.
| Primary Need | Soil | Lift (mm) | Trench/Area Geometry | Suggested Class | Why |
| Fast base course on roads | GW/SW | 220–300 | Open areas | Heavy (50–65 kN) | Balanced force/weight for deep granular lifts |
| Utility backfill, long runs | SP-SM | 180–250 | 650–750 mm trenches | Heavy or Medium-Heavy | Plate width fits, torque for reversals |
| Landscaping/pavers | Sand/Bedding | 80–120 | Tight edges | Light (20–30 kN) | High frequency, gentle amplitude, optional pad |
| Mixed soils on subdivisions | SM/SC | 150–220 | Mixed geometry | 50–70 kN | Versatility across moisture changes |
| Cohesive zones (seasonal) | CL/CH | 120–180 | Confined | 65–90 kN (verify) | Energy + passes; monitor moisture; consider rollers if slow |
Common Sizing Mistakes
Chasing kN numbers without mass/plate to back it up → unstable, bouncy compaction.
Over-wide plates for narrow trenches → wasted passes due to edge losses and scuffing.
Too thick lifts chasing production → density fails, rework.
Ignoring moisture → energy wasted regardless of machine size.
Oversized engine on undersized exciter → fuel penalty with no density gain.
Underestimating reversals & overlaps → schedule slips; plan with realistic efficiency factors.
