Crane and Bridge Construction
ZEDEX® – High-performance plastic solutions
,Plain bearing bush in the steering of gantry pallet trucks
Gantry trucks, are lifting vehicles that transport shipping containers to ports. The containers are raised in the middle between the portal-shaped frame of the pallet truck and can thus be brought to the desired storage location.
The plain bearing bushes are housed in the steering mechanism (steering pin) of the wheels and enable the steering movement of the wheels.
So far, bronze bushings have been used.
High maintenance effort, the bronze bushes must be lubricated. High acceleration forces.
ZX-100K bushings are used as a replacement material
(Ø 280/240 x 150 mm). The sockets operate in dry mode.
The mating surface is spray coated, approx. 68 HRC, rustproof. The sealing is realized by a rod seal. This is installed with two O-rings in an approx. 6 mm deep groove.
After 3 years working the bushings were still in perfect shape since: sealings still in place, wear of only 0.05 mm and no deformation.
Track rollers in the telescopic boom of a work platform
The track rollers serve to guide the telescopic boom of a mobile work platform, which allows a maximum working height of 50 m. The track rollers are pressed on bearings. Cast polyamide has previously been used as the material.
The maximum load is 200 kg, at the maximum working height and up to a lateral outreach of 17 m. With a load of 80 kg, a lateral reach of max. 20 m is possible. The ambient temperature is between approx. -10 ° C and +40 ° C.
Rollers made of ZX-100K are now used, which do not undergo any dimensional changes due to moisture absorption.
The wheels have the following dimensions:
- Outside diameter 100 mm
- Inside diameter 72 mm
- Width 38 mm
So far, no problems have been encountered with the ZX-100K castors.
Slideway in crane booms
In this application, a suitable bearing material for the support of the telescopic boom was sought. The sliding guide is located in the rectangular guide tube in which the boom is guided.
The painted mating-running surface of the boom must not be damaged by the sliding movement for optical reasons.
The guide is also exposed to the weather and direct sunlight. There is a high surface pressure caused by edge pressure.
In addition, vibrations and shocks occur while driving. Dry running, very little wear on the guide material, no damage to the painted mating surface, tight thickness tolerances in the delivery state and absolute dimensional stability in use are required.
After extensive investigations of more than 40 materials and test bench tests, ZX-100K has been released for standard installation. In the future, further bearing zones are to be converted from bronze to ZX-100K.
With a ZX-100K guide, an extension of the telescopic arm is also possible under load. The paint is not damaged and there are no problems in outdoor use.
There is no maintenance due to dry running.
Pedestrian Bridge construction
The sliding pads are located between the supports and the decking of bridges and serve to absorb static forces. In addition, movements, e.g. due to thermal expansion, wind, traffic or earthquakes must be compensated. So far, PTFE has been used for this.
PTFE could not meet the high requirements. It did not withstand the high surface pressures in the long run, which led to permanent deformation after a short time. Therefore, a better alternative material was sought.
PTFE has been replaced by ZX-100K, which allows a permanent surface pressure of up to 30 MPa. ZX-100K has been certified for bridges after extensive tests.
With ZX-100K, the problems of permanent deformation due to creep do not occur.
The wear has been reduced thanks to the excellent tribological properties and the service life has been significantly extended.
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