User Manual

Page 10 of 39 DETROIT DDC-ENG-MAN-0001
NOTES: 1) The maximum bending moment of the Rear PTO to the transmission mounting surface
must be calculated including the length of unsupported hydraulic hoses, and the weight
of the fittings and hydraulic fluid. Support brackets are NOT allowed!
2) The maximum bending moment allowed between the Rear PTO and the DT12 transmission
Is 29.5 lb-ft (40 N-m).
Unless specific information is available on the pump mounting hardware, please use the following formulas
and weights provided below.
 Hydraulic hose fittings: 1.18 lbs each
 Weight of hydraulic fluid:
= (# of hydraulic hoses) * (0.0361) * [(3.142)*((Hose ID/2)
2
) * (Length of hoses to first
clipping point)]
 Weight of hydraulic hose
= (# of hydraulic hoses) * (Hose weight/ft) * (length in feet of hoses to 1
st
clipping point)
 Hydraulic hose weight estimation chart:
Hydraulic Hose
Chart Estimation
Hose I.D.
lbs/ft
1/4
0.16
3/8
0.23
1/2
0.35
5/8
0.44
3/4
0.58
1
0.79
1
-
1/4
1.5
Table 1: Typical hydraulic hose weight estimation chart.
Max Bending Moment = M
pump
+ M
ftgs
+ M
fluid
+ M
hoses
where
M
pump
= Bending Moment of the hydraulic pump (lb-ft)
= (weight of pump in lbs) * [(distance from pump center of gravity to PTO mounting surface in
inches)/12]
If center of gravity is not known, assume this is at ½ the total length of the pump
M
ftgs
= Bending moment of the hydraulic line fittings (lb-ft)
= (# of fittings) *(weight of fittings in lbs) * [(distance of fittings from pump mounting surface in
inches) / 12]
M
fluid
= Bending moment due to the hydraulic fluid (lb-ft)
= (# of hydraulic hoses) * (weight of fluid) * [(1/2 * length of hoses until first clipping point) +
(distance of pump center of gravity to PTO mounting surface)]
M
hoses
= Bending moment due to the hydraulic hoses (lb-ft)
= (# of hydraulic hoses) * (weight of hoses in lbs) * [(1/2 * length of hoses until first clipping
point) + (distance of pump center of gravity to PTO mounting surface)] / 12
If the calculated Bending Moment exceeds the 29.5 lb-ft limit, try shortening the length of the hydraulic hoses
to the first clipping/support point.