T–58
When identifying a shaft center location, each X-Y coordinate is specified with a measurement
in the "X" as well as the "Y" direction. This requires a horizontal and vertical measurement for each
shaft center in order to establish a complete coordinate. Either English or Metric units of measurement
may be used.
A complete coordinate is specified as follows:
(X, Y)
(13-1)
where: X = measurement along X-axis (horizontal)
Y = measurement along Y-axis (vertical)
In specifying X and Y coordinates for each shaft center, the origin (zero point) must first be
chosen as a reference. The driver shaft most often serves this purpose, but any shaft center can
be used. Measurements for all remaining shaft centers must be taken from this origin or reference
point. The origin is specified as (0, 0).
An example layout of a 5-point
drive system is illustrated in Figure 28.
Here, each of the five shaft centers are
located and identified on the X-Y
coordinate grid.
When specifying parameters for the
movable or adjustable shaft (for belt
installation and tensioning), the following
approaches are generally used:
Fixed Location: Specify the
nominal shaft location coordinate with a
movement direction.
Slotted Location: Specify a
location coordinate for the beginning of
the slot, and a location coordinate for
the end of the slot along its path of linear
movement.
Pivoted Location: Specify the
initial shaft location coordinate along with
a pivot point location coordinate and the
pivot radius.
Performing belt length and idler
movement/positioning calculations by
hand can be quite difficult and time
consuming. With a complete
geometrical drive description, we can
make the drive design and layout
process quite simple for you.
SECTION 14 BELT PULL AND BEARING LOADS
Synchronous belt drives are capable of exerting lower shaft loads than V-belt drives in some
circumstances. If pre-tensioned according to SDP/SI recommendations for a fully loaded steady
Fig. 28 Example of 5-Point Drive System
(-4,7)
(8,0)
(3,-1)
(2,2)
(0,0)
-2
2
4
6
8
10
-2
2
4
6
8
10
-4
-6
-8
-10
-4
-6
-8
-10
Y
X
