Bridge And Rails (For Ots And/Or Monitor Suspension) - GE Precision RXi Preinstallation Manual

GE M S
EDICAL YSTEMS
D 5123449-100, R
IRECTION
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5.2.11. Bridge and Rails (for OTS and/or Monitor Suspension)

The stationary rails utilize extruded aluminum channels that are ceiling mounted and are 4400mm in length. The
spacing between these stationary rails accommodates an overhead mounted bridge structure. The bridge length is
3000 mm and the bridge width is 670 mm.
Note: The standard distance of 1650mm between rails can be reduced to as little as 1300mm or increased to as much
as 2000mm.
Maximum flexion between 2 anchoring points
During worst working equipment conditions it is necessary to find out the working stress on each equipment support
The stress force of each equipment part is split into the following items:
P1 = 900 N Rails (14 points anchoring )
P2 = 850 N Bridge (it slides on 4 support bearings)
P3 = 1750 N Carriage (stand with tube, collimator, mechanical and electrical parts)
In order to find out rail flexures, the study must be related to a close rectangular shape that reproduces the rails core
dimensions.
If you work in this way, you will always be able to simplify job calculation and in addition we will always be in a
Safety situation
As a matter of fact rails are more complex, ribs and cores ( that in this study are not taken into consideration) really
add large stiffness to the rails
At the same way for the below calculation, the rail steel plate is not taken into consideration that it is the guide for
sliding bearings and as a matter of fact it does add stiffness to the rails too.
If you make reference to the attached drawing you can calculate rails flexure by taking into consideration the main
involved sizes.
P = 1500 N Half suspension weight and transversal carriage weight
L = 700 mm distance between rail anchoring points
E = 60000 MPa aluminum modulus of elasticity
4
I = 365000 mm inertia module related to the rail section (make reference to the following drawings)
As a result the flexibility of beam rested between extreme sides is calculated by the following formula:
⋅
3
p l
=
f
⋅ ⋅
192
E I
By replacing the value written above, you will be able to find the
searched result
=
. 0 12
f mm
Page 52 / 111
12
EVISION
P
RECISION
June 2009
RX S P -I
I YSTEM RE NSTALLATION