1. Endplay Rb Fapp = W + TH Ru h Lsf Lsmin W EP Lms=Lr-EP Lr force force
Lsf = Length of Spring, Free condition (one spring to represent many)
Lsmin = Length of Spring, MINimum
(upper bearing outer ring bottomed out against housing axial seat)
h = height of rotor above bottomed out (varies with Fapp)
Lr = Length of motor Rotor (bottom of upper brg to top of lower brg)
Lms =Length of Motor Stator
(housing axial seat below upper brg to housing axial seat above lower brg)
EP = End Play = Lr - Lms
(endplay adjustment accomplished by varying Lms for this motor)
Fapp = applied force (Weight + THrust of pump)
Ru = reaction force on rotor from upper bearing
Rb = reaction force on rotor from bottom bearing
K = spring constant (assumed constant if Lsf-Lsmin-EP << Lsmin)
Fspring = K*(Lsf –Lsmin - h) [when not bottomed out]
Static Force balance: Ru = Rb + Fapp
*Simplifying assumption: all parts have stiffness much higher than springs => all others considered infinite stiffness. h
Lsf
Lsmin Lr
Lms=Lr-EP Rb
Fapp = W + TH
force
force
<=Ru with
lower EP
K*(Lsf-Lsmin)
Ru = K*(Lsf-Lsmin- h)
Slope=1
K*(Lsf-Lsmin-EP) Ru
K*(Lsf-Lsmin- EP)-W Rb
<=Rb with lower EP Rb
Fapp h EP W
Fapp = K*(Lsf-Lsmin- EP)
Rb = K*(Lsf-Lsmin- EP)-Fapp

2. Lower Brg Detail - ADJUST ENDPLAY WITH PIECE 10
Inner cap
Spacer (steel)
ENDPLAY ADJUST
Bearing
Bearing nut
Bearing Bracket *
Shaft threads
Lock Washer
Shaft
Centerline * *
Outer Cap

3. Upper bearing – edited to add spring
Bearing Bracket
Upper and lower bearing brackets are attached to opposite ends of motor frame.