1、Paver screed 1.1 Function Fulfilled by the Screed The screed, the road pavers working tool, fulfils the function of uniformly compacting the paving material across the entire pave width and producing a close-textured and level surface. The screeds compacting systems shall pre-compact the mix to the
2、greatest possible extent. This is to minimize the influence of layer thickness upon the amount of subsequent compaction by rolling when bringing about the pavements final density. For pre-compaction, different compacting systems are available: T = Tamper (an eccentric shaft causes the tamper bar to
3、move up and down) V = Vibrators (vibrations are generated by an eccentric shaft acting on the screed plates at right angles to the direction of motion) P = Pressure Bar(s) (the pressure bar(s) are hydraulically pressed onto the mix at a frequency of 68 Hz (approx.) and a maximum pressure of 130 bar)
4、 P1 = Screed equipped with 1 Pressure Bar P2 = Screed equipped with 2 Pressure Bar 1.2 Extending Screeds and Bolt-on Extensions For all VOGELE screeds, bolt-on extensions are available. The VOGELE system of bolt-on extensions allows to easily and sturdily build up screeds to any pave width desired.
5、Even when paving in large widths, VOGELE screeds work with highest precision and achieve superb degrees of uniform density right up to the pavement edges. When fitting bolt-on extensions, care must be taken to ensure that the bottom edge of the screed plate is flush with the adjacent units, otherwis
6、e a step may be produced in the pavement or the screed planning angle may change. During the paving process, this can have a negative effect on pre-compaction, surface structure and floating behaviour of the screed. 1.3 Set-Up of the Extending Screed 1. Position both extending units in place so that
7、 the screed plate of the basic unit and the screed plates of the extending units are roughly level. 2. Slacken the chains connecting the spindles on the extending unit so that each spindle can be adjusted independently. 3. Carefully lower the screed onto the extending units. Timber should be placed
8、under the middle of the two extending units. 4. Now adjust the screed planning angle via the tow point rams so that the screed plate rests on the timber. 5. Remove the locking screw from the threaded bush on all spindles. 6. Adjust all threaded bushes. 7. Refit the locking screws. 8. Raise the scree
9、d and secure it so that it cannot sink. 9. Lay a ruler along the inner and outer spindle pairs and then adjust the height of the extending unit via the front and rear spindles with the aid of a special wrench, so that the screed plate of the basic unit is level with the trailing edge of the extendin
10、g unit. Now adjust the planning angle of the extending unit via the front spindle. 10. Reconnect the spindle pairs with the chains. 11. Raise the frame of the extending unit by approx. 4mm so that it roughly corresponds to the planning angle of the screed. 12. During the first on-site job, the heigh
11、t of the extending units must be corrected until a longitudinal step is no longer visible. 1.4 Fixed-Width Screeds 1.4.1 Compacting Systems Installed in Fixed-Width Screeds TV = Tamper and Vibrators Installed in: - SB 250 - SB 300 Recommended for: - All conventional mixes. - Materials which are easy
12、 to compact or thinner pavement layers. - Jobs where paving can be done in a largely constant width. - Large radii. TP2 = Tamper and 2 Pressure Bars Installed in: - SB 250 (and Hydraulic Bolt-on Extensions) - SB 300 (and Hydraulic Bolt-on Extensions) Recommended for: - All conventional mixes. - A sc
13、reed in TP2 version achieves a high pre-compaction even of thick pavement layers. - Mixes which are difficult to compact on account of their grain shape and consistency. - Jobs where paving can be done in a largely constant width. - Large radii. - Less effort required for subsequent compaction by rolling. TP1 = Tamper and 1 Pressure Bar
