PRONAR Dolly Tandem 18 t, JOST-Sattelkupplung, Luftfederung
€21,705.00
Standard equipment
- Chassis frame made from robust steel, welded from I-sections
- JOST fifth-wheel coupling, 18 tonnes, adjustable in three positions on the frame
- Pneumatic tandem suspension with 1.310 mm wheelbase, rigid axles, drum brakes Ø 406 × 120 mm
- Air suspension system with raise and lower function
- Y-shaped drawbar with swivelling drawbar coupling and towing eye Ø 50
- Dual-line compressed-air braking system with ALB Premium
- Pneumatic parking brake with adjustment device
- Telescopic drawbar support with single-speed gearbox
- Braking system connections for the semi-trailer: red plug (power supply), yellow plug (control), 7-pin ABS socket above the drawbar
- Single-line hydraulic system for connection to the semi-trailer's tipping cylinder
- Hydraulic connection above the drawbar
- Coiled hoses for the lighting system and hydraulic system
- 12 V LED lighting system with side marker lights, rear lights with protective grille
- 24 V on-board power supply output with 12V/24V converter: one 15-pin and two 7-pin sockets
- Plastic mudguards in front of and behind the wheels
- Approved rear underrun protection
- Folding rear apron
- Wheel chocks with holder
- Paint finish: black grey RAL 7021
Technical data
| Manufacturer | PRONAR |
|---|---|
| Product type | Tandem dolly for semi-trailers |
| Permitted gross weight | 18.000 kg (fifth wheel adjusted fully forwards) |
| Technically permitted gross weight (on-site use) | 21.000 kg |
| Unladen weight | 2.925 kg |
| Overall dimensions L × W × H | 4.630 × 2.525 × 1.730 mm |
| Maximum width with semi-trailer | 2.550 mm |
| Maximum height with semi-trailer | 4.000 mm |
| Fifth-wheel height, ready to travel | 1.200 – 1.300 mm (depending on suspension setting) |
| Fifth-wheel coupling | JOST, 18 t, adjustable in three positions |
| Track width | 2.050 mm |
| Wheelbase | 1.310 mm |
| Suspension | pneumatic, tandem |
| Nose weight | 3.000 kg |
| Tyres | 385/65 R 22,5 |
| Maximum speed | 40 km/h |
| Required tractor power | 182 PS / 133,8 kW |
Note: The trailer is intended for transporting a semi-trailer on site. Transport on public roads is possible subject to compliance with regional regulations. The single-line hydraulic system requires a permanent connection to the tractor hydraulics. All listed parameters apply to individual approval in Germany.
Product description
What a dolly does
A dolly is an intermediate vehicle with a fifth-wheel coupling. It turns a tractor into a towing vehicle for lorry semi-trailers.
Why this is of interest to many businesses:
- Use existing semi-trailers. Businesses that already have semi-trailers in their fleet – for grain, silage, wood chips or building materials – can move them without a tractor unit.
- Between field and farm. The lorry collects the semi-trailer at the field edge, and the tractor tows it over unpaved tracks.
- No second towing vehicle. The farm tractor does the job.
- Significantly cheaper than owning a tractor unit – in terms of purchase price, tax and insurance.
Fifth-wheel coupling adjustable in three positions
The 18-tonne JOST fifth-wheel coupling can be fitted to the chassis frame in three positions.
Why this matters: The position determines the load distribution between the dolly axles and the tractor coupling.
- Fifth wheel further forwards – more load on the tractor coupling, with a higher permitted gross weight of 18.000 kg. Nose weight increases to up to 3.000 kg.
- Fifth wheel further back – more load on the dolly axles, less nose weight on the tractor.
The figures of 18.000 kg gross weight and 3.000 kg nose weight apply when the fifth wheel is adjusted fully forwards. This is something to clarify before use.
Air suspension with raise and lower function
The pneumatic tandem suspension can be raised and lowered. When ready to travel, the fifth-wheel height is between 1.200 and 1.300 mm.
How this helps when coupling: The dolly is lowered and driven under the semi-trailer's kingpin, then raised. Without height-adjustable suspension, the semi-trailer would have to be raised to exactly the right height using its landing legs – a laborious process that is unsafe on uneven ground.
When travelling, the air suspension cushions the semi-trailer and its load – protecting the frame, load and driver.
Complete connection equipment for the semi-trailer
A semi-trailer needs more than a mechanical connection. The dolly provides all the necessary interfaces:
| Brakes | Red plug for power supply, yellow plug for control |
|---|---|
| ABS | 7-pin socket above the drawbar |
| On-board power supply | 24 V output with 12V/24V converter, one 15-pin and two 7-pin sockets |
| Hydraulics | Single-line system for the tipping cylinder, connection above the drawbar |
The 12V/24V converter is key: tractors operate at 12 V, while lorry semi-trailers use 24 V. Without a converter, the semi-trailer's lights would remain dark.
Moving tipping semi-trailers
The single-line hydraulic system supplies the semi-trailer's tipping cylinder.
What this makes possible: The semi-trailer can be tipped using the tractor – in a silage clamp, at a stockpile or on a building site. Without this connection, the dolly would be a means of transport, not a working implement.
Requirement: The system needs a permanent connection to the tractor hydraulics.
As optional equipment, a separate hydraulic system with a 150-litre oil tank, pump and telescopic PTO is available, electrically controlled from the tractor cab.
When is this worthwhile? When the tractor does not have enough oil capacity for the tipping cylinder of a large semi-trailer – or when different towing vehicles are used.
ALB Premium fitted as standard
The dual-line compressed-air braking system with ALB Premium and 406 × 120 mm drum brakes is part of the standard equipment.
Why this is essential here: The load on the dolly axles varies considerably – from an empty dolly to a loaded semi-trailer. Without load-dependent control, the brakes would either be too strong or too weak.
A pneumatic parking brake with adjustment device secures the parked combination.
Swivelling drawbar coupling
The Y-shaped drawbar has a swivelling coupling with a towing eye Ø 50.
Why the swivel matters: When a combination of tractor, dolly and semi-trailer is on uneven ground, it twists. A rigid connection would transfer these forces to the drawbar and frame.
Alternative at no extra cost: Lower hitch with a rigid towing eye Ø 40. A K80 ball coupling is available as optional equipment.
Road approval – what to bear in mind
The manufacturer expressly states: The trailer is intended for transporting a semi-trailer on site. Transport on public roads is possible subject to compliance with regional regulations.
What this means in practice: Whether it is permitted depends on the combination of tractor, dolly and semi-trailer – and on the semi-trailer's own approval status. This should be clarified with the vehicle registration authority and sales adviser before purchase.
Dimensions of the combination
- Width with semi-trailer: maximum 2.550 mm
- Height with semi-trailer: maximum 4.000 mm
The 4-metre limit must be observed – above this height, a permit is required for transport, and many farm entrances and underpasses are lower.
Additional equipment
- Lower hitch with rigid towing eye Ø 40 (no extra cost)
- K80 ball coupling
- Hydraulically folding drawbar support with shut-off valve
- Separate hydraulic system with 150-l oil tank, pump and telescopic PTO, electrically controlled
- Warning triangle for slow-moving trailers
Applications
Contractors with semi-trailers, large arable farms, biogas plants and substrate logistics, wood-chip and biomass logistics, transport companies with mixed fleets, businesses with loading areas away from paved roads.
Operating notes
- Clarify road approval before purchase – the dolly is primarily intended for on-site transport; road use is subject to regional regulations.
- Adjust the fifth-wheel position to suit the desired load distribution – the gross weight and nose weight figures apply when the fifth wheel is adjusted fully forwards.
- Check the towing vehicle's nose weight capacity: up to 3.000 kg.
- The single-line hydraulic system requires a permanent connection to the tractor hydraulics.
- Before coupling, set the air suspension to the appropriate fifth-wheel height.
- Check the kingpin and fifth-wheel coupling are locked before every journey.
- When tipping the semi-trailer, ensure the ground is level and firm, and do not work beneath overhead power lines.
- Observe the permitted combination height of 4.000 mm.
- Keep everyone clear of the space between the dolly and semi-trailer when coupling and uncoupling.
- Retighten the wheel nuts after the first few hours of operation and regularly thereafter.
Frequently asked questions
What is a dolly?
An intermediate vehicle with a fifth-wheel coupling. It turns a tractor into a towing vehicle for lorry semi-trailers – without the need for a dedicated tractor unit.
How much can the combination weigh?
18.000 kg permitted gross weight when the fifth wheel is adjusted fully forwards; technically 21.000 kg for on-site use.
Why is the fifth-wheel coupling adjustable?
Its position determines the load distribution between the dolly axles and the tractor coupling. Further forwards means more nose weight on the tractor and a higher permitted gross weight.
What is the air suspension with raising function for?
The dolly is lowered and driven under the kingpin, then raised. Without height-adjustable suspension, the semi-trailer would have to be aligned precisely using its landing legs – an unsafe process on uneven ground.
Can I use it to unload a tipping semi-trailer?
Yes. A single-line hydraulic system supplies the semi-trailer's tipping cylinder. It requires a permanent connection to the tractor hydraulics. A separate hydraulic system with a 150-l tank is available as optional equipment.
What is the 12V/24V converter for?
Tractors operate at 12 V, while lorry semi-trailers use 24 V. Without a converter, the semi-trailer's lights would remain dark.
Can I use it on public roads?
The manufacturer specifies the dolly for on-site transport. Road use is possible subject to regional regulations – this should be clarified with the vehicle registration authority before purchase.
What tractor do I need?
182 PS or 133,8 kW, and a coupling rated for 3.000 kg nose weight.