8258 - Crane Truck

Details: Category: Greater Than 1000pcs Sets; Hits: 211

2009

Set Year: 2009
Set Number: 8258
Set Parts: 1877
Building Instruction: No
Currency: na

Great set and good scale for all kinds of different truck MOCs you can use this set as a starting point.

Functions/complexity

Gear box vertically orientation
switch to turn direction of the motor spin direction

4 functions:

upper hinge crane
lower hinge crane
slewing of crane
out riggers

All powered by one 9V Power Functions XL motor.

Cabin/engine

The cabin is fairly realistic and hinges over the front revealing the 6 cylinder engine. The downside is missing working doors. There are though very nice MOCs on rebrickable.com.

Crane

Some records:

set with most usage of part 'Technic, Pin Connector Perpendicular 3L with 4 Pins' for a 24 times! (by 2023)

Main model

Features

Steering

This crane truck is a heavy beast, hence the 4-axle or 8 wheel base. Due to the heavy crane just behind the cabin 2 axles are needed in the front to carry the weight of the crane. This in turn means a double axle steering construction. With double steering you need to make sure for smooth curve driving the 2nd pair of wheels need to turn in a sharper way to follow the smaller inner circle of the turn. It is a pitty that only the earlier sets have Ackermann steering which would made the turning of this truck even better. The ratio between the front and 2nd axle steering is 20:12. All in all it makes steering smooth, however due to missing Ackermann steering there is slip in turning. Steering is only possible by HOG-steering. There are though some nice MOCs with a steering wheel in the cabin connected. This truck by the way has a nice scale for technic minifigs.

Engine and Cabin

This is a heavy truck with a huge crane on top. This needs a big engine. The set contains a 8 cylinder engine, that can be reach, like in traditional real trucks, by tipping the cabin of the truck. This gives good access to the engine. The engine is moved by the 3^rd pair of wheels from the front via a differential. In front of the engine a fan that moves with the engine when the truck is moved forwards to complete the full experience.

Hoist

A hoist is positioned on the side of the crane and manually operated which uses LEGO® string to lift a metal hook. A Gear 12 Tooth Double Bevel is used as knob to operate the hoist. Just next to it a Gear 16 Tooth that acts as a ratchet which mates with a pawl, which supports the tension in the cable together with the weight of the metal hook. This is all on a single axle with a string reel drum to guide the winding of the string properly. The crane is designed very compact which causes the manual hoist, because there is literary no room for an other driving shaft for the hoist. Another option would have been to place the hoist under the turn table to give room for a powered hoist.

Power Functions

text

Gearbox

The gearbox, to handle the 4 different functions is a piece of genius working with the possibilities of Lego Technic. Where in general the gearbox has a horizontal orientation this one is in majority oriented in vertical direction. Especially the usage of the linear actuator base to redirect in 90^o the turn direction of power is genius. This makes it possible to cramp 4 different functions in such a small space. By applying a switch you can easily change direction as well and play with this crane as a real operator. The 4 functions clock wise starting left top moving the outriggers, moving up and down lower crane arm and finally moving up and down the upper arm of the crane. Finally with the red colored parts it is indicated what gears are continuously turning when the motor is switched on

Slewing

The slewing for this crane is fully mechanical and not a mix with pneumatics. This means no strain on hoses so this crane can turn 360^o degrees. Because the turning is slowed down dramatically this can be easily handled with the rest of the functions to give a realistic effect and good playability.

Crane and telescope boom