Nilfisk-Advance BA 750/850ST, Service Manual

Page: 22 / 69

FORM NO. 56043071 CMAX ™ 28/34ST / I-MAX ™ 28/32C, BA 750/850ST, BA 750C - 21
SCRUB BRUSH SYSTEM
M
BL
K
A1
C
ont
ro
l B
o
ar
d
RE
D
GR
N
F2
1
2
Ci
rc
ui
t Br
eak
er
5 A
m
p
S3
Sw
itc
h
SPST
Ke
y
GR
N
BL
K
/W
H
T
4
13
B-
2
B-
3
M5
M
VI
O
/YEL
WH
T
/G
R
N
Mo
to
r
Br
us
h A
ct
uat
or
14
B+
2
1
B+
1
BR
N
5B
RUS
H CO
NT
A
C
T
O
R
VI
O
/BL
K
BR
N
K1
Co
il,
B
ru
sh
M
ot
or C
on
tac
to
r
11 12
B
RUS
H A
C
T
U
A
T
O
R
-2
B
RUS
H A
C
T
U
A
T
O
R
-1
R EM O VE RE L AY
F O R /R E V
B R U SH M O TO R
B -1
GR
A
/B
LK
2
8
3
1 0
G RA /B L K
YEL
BL
K
W HT /G R A
WH
T
/G
R
A
BL
K
M3
M2
M
Mo
to
r,
Ri
gh
t B
ru
sh
Mo
to
r,
L
eft B
ru
sh
PO
L
ARI
T
Y
F
O
R DI
S
C
BRUS
HE
S
+
-
+
-
R1
PO
T
, 5
K
O
hm T
hr
ottl
e
PO
L
ARI
T
Y
F
O
R CY
L
INDRI
CAL
BRUS
HE
S
+
-
+
-
M3
M
M2
M
Mo
to
r,
Ri
ght
B
rus
h
Mo
to
r,
L
eft B
ru
sh
WH
T
/G
R
A
BL
K
WH
T
WH
T
RE
D
K1
K3
B LU /W H T
C
ont
ac
t, B
rus
h R
em
ov
e
Op
tional
A2
1208 S
p
eed
C
o
n
tr
o
lle
r
B-
(T
2)
B+
(T
1)
B+ B-
P2
(T
3)
M1
(T
4)
M2
P1
1 2
1 2 3 4 5 6
OU
T
P
U
T
OU
T
P
U
T
KEYSW
IT
C
H
R
EVER
SE
WI
PER
FO
R
W
A
R
D
+
-
VI
O
BR
N
/W
H
T
GR
N
/YEL
1 3
2
PO
T
, 25K
O
hm
S
peed Li
m
it
1 2
2
3
1
RE
D/
B
LK
GR
A
R2
-
+
Re
la
y,
B
rus
h R
em
ov
e
(O
pt
ional
)
BR
N
OR
N
/B
LK
K3
BL
K
- The brush remove circuit sequence starts when the operator depresses the control panel scrub off/brush pressure decrease button (H)
activating the A1 board’s brush remove function. This triggers (starts) an internal timer relay closing the K1 coil ground circuit, pin #5 (Vio/
Blk wire) turning on momentarily the brush solenoid to run the brush motors.
- Simultaneously with the K1 coil being turned on the same input command connects the battery ground connection through the A1 pin #10
wire (Org/Blk) to the K3 coil turning it ON.
- This pulls in the K3 load contact connecting it to the battery ground return.
- The next step is the board timer turning off the K1 brush solenoid and connecting the normally Pos. motor load circuit to a battery ground
return (through the K3 load contact and K1 normal closed contact).
- With two battery ground inputs at the brush motors this circuit causes a short to ground and the motors stop abruptly. The built up brush
inertia easily spins the brushes off the motor drive disc lugs.
FIGURE 1
• Control and Load circuit detail (continued)