How to Select a Hydraulic Lifting Differential Drive for 6β20 Ton AGV
A hydraulic lifting differential drive combines vehicle traction, differential steering and vertical lifting in one heavy-duty module. It can reduce the number of separate drivetrain and lifting assemblies in AGVs that must move and raise large loads.
But the module should not be selected from load capacity alone. For a 6β20 ton AGV, tractive force, driven-wheel load, travel speed, wheel size, lifting requirement, hydraulic pressure and electrical architecture all need to be checked together.
1. Understand What the Module Is Doing
The two driven wheels use independent servo motors. Forward travel, turning and pivot rotation are produced by controlling the speed difference between the wheels, while the hydraulic system provides vertical lifting within the same assembly.
The current JY Robot series uses absolute steering-angle feedback, a 100 mm hydraulic lifting stroke, 16 MPa system pressure and 4β20 mA lifting-position feedback.
2. Compare the Real 6β20 Ton Configurations
| Load | Motor | Voltage | Wheel | Speed | Rated Traction |
|---|---|---|---|---|---|
| 6,000 kg | 2.5 kW Γ 2 | 48 V | Γ300 Γ 100 | 0β29 m/min | 5,307 N |
| 8,000 kg | 2.5 kW Γ 2 | 48 V | Γ300 Γ 135 | 0β29 m/min | 5,307 N |
| 10,000 kg | 2.5 kW Γ 2 | 48 V | Γ300 Γ 165 | 0β29 m/min | 5,307 N |
| 15,000 kg | 3.0 kW Γ 2 | 48 V | Γ400 Γ 165 | 0β38 m/min | 4,775 N |
| 20,000 kg | 4.0 kW Γ 2 | 96 V | Γ450 Γ 200 | 0β31 m/min | 7,903 N |
All five listed configurations use a 100 mm lifting stroke and 16 MPa hydraulic system pressure. The lifting-position sensor uses a 24 VDC supply and provides a 4β20 mA output signal.
3. Load Capacity and Tractive Force Are Not the Same Thing
The table shows an important point: rated load capacity does not increase in direct proportion to rated tractive force.
The 6, 8 and 10 ton configurations are all rated at 5,307 N, while the 15 ton configuration is rated at 4,775 N. The 20 ton configuration increases to 7,903 N.
That means a higher load-capacity model should not automatically be treated as a higher-traction model. The actual vehicle requirement must be calculated from rolling resistance, acceleration, slope, driven-wheel load and operating conditions before the configuration is selected.
4. Calculate Vehicle Traction Before Choosing the Load Class
Start with the actual vehicle requirement rather than the model name. A preliminary straight-line calculation normally includes rolling resistance, acceleration and grade resistance:
F = Frr + Fa + Fgrade
After the required tractive force is known, compare it with the rated traction of the candidate configuration. A higher load-capacity model is not automatically a higher-traction model: the 15 ton configuration is rated at 4,775 N, while the 6β10 ton configurations are rated at 5,307 N.
5. Check Driven-Wheel Load and Available Friction
The drive wheels can only transmit force if sufficient normal load reaches them. Usable traction is limited approximately by:
Fmax = ΞΌ Γ Ndrive
Heavy AGVs often use separate support wheels, so gross vehicle mass and driven-wheel load are not the same number. Centre-of-gravity position, payload transfer and support-wheel arrangement should therefore be checked together with motor torque and rated traction.
6. Use the Complete Configuration, Not One Specification
| Engineering Input | What to Check |
|---|---|
| Vehicle load | Actual load carried by the drive module and driven wheels |
| Traction | Rolling resistance, acceleration, slope and turning resistance |
| Wheel size | Γ300β450 mm range, floor condition and installation space |
| Travel speed | 0β29, 0β38 or 0β31 m/min depending on configuration |
| Electrical system | 48 V for 6β15 ton configurations; 96 V for the 20 ton configuration |
| Lifting | 100 mm stroke, 16 MPa hydraulic system and 4β20 mA position feedback |
The final configuration should satisfy these conditions at the same time. Selecting only from rated load can result in insufficient traction, unsuitable wheel geometry or an electrical architecture that does not match the vehicle.
7. When an Integrated Hydraulic Lifting Drive Makes Sense
An integrated hydraulic lifting differential drive is most useful when the same heavy-duty module must provide vehicle traction, pivot turning and a 100 mm lifting function within one assembly.
A separate lifting architecture may be more appropriate when the project requires a substantially different stroke, a lifting point located away from the drive module, or independent maintenance and packaging of the drive and lifting systems.
For the available 6β20 ton configurations, see the hydraulic lifting differential drive module. For a broader comparison of lifting technologies, see ball screw, trapezoidal screw and hydraulic lifting selection.
8. Screening Example: 10, 15 and 20 Ton AGVs
To show why load class alone is not enough, consider three illustrative vehicles under the same operating assumptions: rolling-resistance coefficient 0.015, acceleration 0.08 m/sΒ² and maximum grade 0.5%. The 20% allowance below is only a screening example, not a universal design rule.
| Vehicle Mass | Base Traction | +20% Target | Module Rating | Preliminary Result |
|---|---|---|---|---|
| 10,000 kg | β 2,762 N | β 3,314 N | 5,307 N | Passes this traction screen |
| 15,000 kg | β 4,143 N | β 4,972 N | 4,775 N | Meets base requirement, but not the illustrative 20% target |
| 20,000 kg | β 5,524 N | β 6,629 N | 7,903 N | Passes this traction screen; 96 V electrical system required |
The 15 ton example is especially important. Its rated load capacity is higher than the 10 ton model, but its rated tractive force is lower. Under the assumptions above, it meets the base straight-line requirement but falls about 197 N below the illustrative 20% target.
This does not mean that the 15 ton configuration is unsuitable for every 15 ton AGV. It means the actual slope, acceleration, rolling resistance, driven-wheel load and required design margin must be checked before approval.
9. When the Preliminary Selection Must Be Reconsidered
- Higher simultaneous slope and acceleration: both increase the required tractive force.
- Insufficient driven-wheel load: available tyre-floor friction may limit usable traction before the motor reaches its rated value.
- Frequent pivot turning: tyre scrub can become more demanding than straight-line travel.
- Different lifting stroke: the listed configurations use 100 mm stroke, so a substantially different requirement may need another lifting architecture.
- Electrical mismatch: the 20 ton configuration uses 96 VDC rather than 48 VDC.
- Installation-space conflict: wheel diameter, hydraulic components and chassis structure must fit the available envelope together.
The final selection should therefore be confirmed from the complete vehicle requirement, not from load capacity, motor power or tractive force as isolated catalog values.