The Jeep Dolly: (Dolly sits between the truck and the gooseneck)
A jeep dolly is an extra axle that can be fitted under the gooseneck, forming an additional axle on the truck. With this extra axle it allows more pressure on the gooseneck. The big advantage of the jeep dolly is that its compact and easy to connect and disconnect. Because the dolly is fitted with a fifthwheel it works the same as connecting or disconnecting the truck and trailer. The jeep dolly is quite compact and does not increase the combination length by much and the low tare weight does not make a big difference to the overall combination weight.
Advantages
+ Short combination length
+ Low tare weight of combinations
+ Small turning circle due to double pivot point
+ Standard Truck
+ Lower “Cost Of Ownership”
+ Lower purchase cost
+ Easy to operate
+ Does not need to be used for lighter loads
Disadvantages
- High coupling height gooseneck
- Dependence on the Jeep Dolly
- Reversing takes practice
- Limited to Max. 4 axle Jeep Dolly
- Permitted axle loads differ per country
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LOW LOADER
The loading floor of a low loader is "recessed" in relation to the bogie height. This enables the operator to transport high loads with clearance under bridges and tunnels.
PAYLOAD
If you want to increase the trailer payload you would normally add additional axles under the loading floor, but with a low loader this is not a practical solution with the lowered deck. The solution would be to add extra axles to the rear bogie, but this limited to 3 axle low loader because of the weight distribution between king pin and rear bogie.
WEIGHT DISTRIBUTION
If more axles are added to the rear bogie the low loader will become heavier and only gets more payload at the back. Therefore the centre of gravity of the load will move towards the rear bogie.
To achieve this axles should be added both at the front and rear to increase the trailer capacity and correctly position the centre of gravity,
To do this the chassis would also require strengthening.
LOAD CAPACITY
There is only one way to increase the loading capacity at the rear, that is to add additional axles, which means more steel and extra weight.
There are four options for increasing the load capacity at the front of the loading floor, each with its own advantages and disadvantages. The ‘’multi axle truck’’, the Jeep Dolly, the Fixed dolly at neck and a Removable dolly
