John Deere stx38 - Manual (Page 243)

3/21/97
6 - 11
HYDROSTATIC POWER TRAIN THEORY OF OPERATION
K50 Version Shown
When in neutral, the shift lever (D), shift bracket (F),
turnbuckle link (E), bellcrank (G), link strap (H), and
shifter shaft lever (I) hold the shifter shaft (J) and the
variable-angle pump swashplate (O) in the neutral
position. While in neutral (level) position, the pump
cylinder block (N) rotates with the pump (input) shaft
but does not pump any oil into the motor half of the
center block (P) because the pump pistons are not
moving up and down as they rotate. Therefore, the
motor cylinder block (Q) does not turn nor do the motor
(output) shaft (M), differential assembly (L), or drive
axles (K and R).
Forward:
K50 Version Shown
When the shift lever (D) is moved into forward position,
the shift bracket (F) pivots, pulling the turnbuckle link
(E) rearward, pivoting the bellcrank (G), link strap (H),
shifter lever (I), shifter shaft (J), and variable-angle
pump swashplate (O) into forward position. With the
pump swashplate angled in forward position, the pump
cylinder block pistons (N) are pumping oil through one
side of the center block (P) into the motor half of the
center block, turning the motor cylinder block (Q)
against it’s fixed-angle swashplate and causing the
motor (output) shaft (M), differential assembly (L), and
drive axles (K and R) to turn in the forward direction.
D
M55850
M58252
F
D
E
G
J
M58253
H
I
E
M58268
J
O
P
N
Q
M
R
K
L
J
N
O
P
Q
M L
R
K
M58270