How do I choose
the dolly (type) and Why?
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How do I choose
the dolly (type) and Why?
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.
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. This is also the case when you extend a semi low loader, read more here.
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 loading floor, each with its own advantages and disadvanges:
Option 1: the ‘’multi axle truck’’
Advantages
+ Short combination length
+ Low tare weight of combination
+ Easy to operate
+ Easier to control
+ Auxiliary steering on all axles of the low loader
Disadvantages
- Long + heavy gooseneck
- Heavy duty loading floor due to increased neck length
- Expensive Truck
- Dependence on one particular truck
- Limited to 6 axle truck
- Larger turning circle
- Can only be sold as combinations
- Not legal in every country
Option 2: 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
Option 3 and 4: The dolly
(Dolly sits between the gooseneck and low bed)
A dolly is designed to sit between the gooseneck and the lowbed. This the loading capacity and also the loading floor. This last point is unique to a Broshuis pendle axle low loader This is because the dolly can be used to support the load. Thanks to the dolly the weight is better distributed between the neck and rear bogie. This configuration allows the operator to carry a bigger and diverse loads. The Dolly comes in two variants, a fixed dolly on the neck, or a removable dolly.
Option 3: Fixed dolly at neck
Advantages
+ Normal coupling height gooseneck
+ Standard Truck
+ Permitted bogie load at least 12T/ line
+ Lighter low bed
+ Easy to operate
+ Axles liftable
+ Auxiliary steering on all axles of the low loader
Disadvantages
- Longer combinations
- Higher tare weight combinations
- Larger turning circle
- Higher maintenance cost
- High purchase cost
Option 4: Removable dolly
Advantages
+ Normal coupling height gooseneck
+ Low loader can be used without dolly
+ Standard truck
+ Permitted bogie load at least 12T/line
+ Lighter low bed
+ Easy to operated
+ Dolly axles liftable
+ Auxiliary steering on all axles of the low loader
+ Can be converted to a semi low loader
+ Possible to link more axle lines
Disadvantages
- Longer combination
- Higher tare weight combination
- Larger turning circle
- Higher “cost of ownership”
- Higher purchase value
- Operation requires experience
- More complex hydraulic, air and electrical systems
Semi Option: dolly on semi low loader
In our 100T Range, it is also possible to have a dolly on a semi low loader with SL or PL axels. In this case, you can use the dolly for weight distribution when the semi is extended. When extending a semi, the centre of gravity moves to the front side of the trailer. By attaching a dolly between the gooseneck and the axle bogie, you increase the trailer capacity on the front side and improve the centre of gravity position.
Next to this, it also gives flexibility in configuring the semi. Retracted, the dolly gives extra load capacity to the trailer and the dolly can be removed if less load capacity is needed to create a shorter combination.
Advantages
+ Normal coupling height gooseneck
+ Semi loader can be used without dolly
+ Standard truck
+ Permitted bogie load at least 12T/line
+ Lighter semi
+ Easy to operate
+ Dolly axles liftable
+ Auxiliary steering on all axles of the semi low loader
+ Possible to link more axle lines
Disadvantages
- Longer combination
- Higher tare weight combination
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