Flat Strike-off Adjusted Too Low
Figure 26
RESULTS OF IMPROPER STRIKE-OFF
Paving With Extended Screed
When the strike-offs are too low the following wear
Figure 28
and operational difficulties will be encountered. (See
EXTENSION OF SCREED
Figure 26).
The screed length can be extended in order to lay a
1. Insufficient amount of material will be metered
mat wider than 10 ft. Mat widths up to and including
to the screed. Therefore, in order to maintain mat
20 ft. can be laid. Screed extensions come in various
thickness, it is necessary to tip the front of the screed
widths and can be attached to either end of the
up. Continued operation of the screed in this manner
screed.
may cause wear on the trailing edge of the screed.
Each 6", 12" and 24" extension is supplied complete
2. Fines will collect at the front edge of the screed
with cover, moldboard extension, and adjustable
directly behind the strike-offs which will build up and
strike-off extension.
cause tearing and voids in the mat. The strike-off will
frequently catch and drag large stone, with the result
that a streak is made in the mat. When this occurs
often, stop paving, raise the strike-off, and try again.
When the strike-offs are too high the following wear
and operational difficulties will be encountered. (See
Figure 27).
1. Too much material will be metered to the
screed. Therefore, in order to maintain a relatively
thin mat thickness, it is necessary to tip the front of the
12 Inch Extension On LH End Of Screed
screed down with the hand wheel adjustments. With
Figure 29
the screed in this position for any length of time, rapid
All parts of the extension are shipped loose and
wear on the leading edge of the screed will occur.
must be assembled in the field. Some careful work is
2. Poor mat textures and low compaction of the
required to align each extension bottom to the screed
mat will prevail under these conditions.
bottom, the moldboard extension to the moldboard,
3. Erratic control of the screed will be noticeable
and the strike-off plate extension to the strike-off
when making minor adjustments.
plate.
A double set of shim packs is supplied with each
extension so that an adjusted shim pack can be kept
inside the extension at its proper corner location.
(See Figure 30). The lengthy job of fitting the
extension bottom to the screed bottom need not
be repeated each time the extensions are
installed. Re-installation of the two correct shim
packs will quickly restore alignment and no time is
lost. The moldboard shims can also be attached at
their respective locations to save time aligning the
extension moldboard.
Flat Strike -off Adjusted Too High
A step by step procedure for assembly and
Figure 27
installation of an extension is shown on the following
pages.
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