Topcon mmGPS 3D Paver, Reference Manual, Page: 164 / 288

Paving Principles
mmGPS 3D Paver Reference Manual
4-2
How a Screed Works
The screed on all modern pavers is of the “floating, self leveling”
type. As the paver tows the screed unit forward, paving material
flows under the screed. This causes the screed to float on the mat of
material, thus establishing mat thickness. Since the screed is mounted
to the paver only at the tow points, the screed is completely free to
float up or down (Figure 4-2). The screed always seek it’s own
“Planning Angle”, or angle of attack, dependent on the combination
of forces acting upon the screed (Figure 4-2).
Figure 4-2. Tow Point Path and Planning Angle
• If the screed angle of attack is increased, the screed rises,
increasing the mat thickness (Figure 4-3).
• If the screed angle of attack is decreased, the screed settles,
providing a thinner mat surface (Figure 4-3).
Figure 4-3. Screed Determines Mat Thickness
Tow Point Path
Existing
Surface
Screed Angle of Attack