Sharp R-267LST Bedienungsanleitung PDF herunterladen (Seite 19)

4,309,917

21

bolt

portion

secured

to

spool

364

and

locked

in

the

adjusted

position

by

a

locknut.

Valve

sleeve

366

has a reverse

return

port

371

and

a

forward

return

port

372

and

is

slidable

in

bore

373

in

valve

body

169.

Spring

374

in

spring

chamber

376

in

valve

body

169

is

seated

on

spring

seat

375

and

engages

abutment

380

on

one

end

of

valve

sleeve

366

and

biases

valve

sleeve

366

to

the

reverse

position

shown,

with

the

other

end

engaging

piston

377,

which

also

is

sliclable

in

bore

373

in

the

valve

body

169,

and

abuts

the

end

wall

378.

In

forward

manual

range,

forward

signal

line

288

supplies

forward

signal

pressure

to

chamber

379

in

bore

373

in

valve

body

169

between

end

wall

378 and

piston

377

and

valve

sleeve

366

so

its

opposite

end

engages

spring

seat

375

wall

with

sleeve

366

in

forward

position.

Exhaust

381

vents

the

bore

365

of

valve

sleeve

366

between

piston

377 and

land

b

of

spool

364 and

bore

373

in

valve

body

169.

At

the

other

end

of

valve

sleeve

366

these

bores

365

and

373

are

vented

past

spring

seat

375

wall.

The

lst

or

low

return

line

339,

which

in

neutral

is

always

supplied

since

it

is

fed

by

both

neutral

advance

line

264 and

return

line

205

and

which

in

lst

and

reverse

ratio

ranges

is

supplied

only

by

return

line

205,

is

con

nected

via

supply

port

382

to

the

space

between

lands

a

and

b

of

spool

346

for

selective

connection

by

reverse

return

port

371

to

reverse

return

line

383

and

lst

for

ward

return

port

372

to

lst

forward

return

line

384.

These

reverse

and

lst

forward

return ports

371

and

372

are

formed

in

sleeve

366

as

a

plurality

of

progressively

wider

slots

with

the

narrowest

slot

of

each

port

at

the

regulating

edge

respectively

of

lands a

and

b

of

spool

364

so

flow

to

reverse

or

lst

forward

return

lines

383

or

384

is

proportional

to

the

degree

of

error

or

deviation

from

the

desired

1st

and

reverse

ratio

range

anti-hunting

or

bias

positions

so

the

rate

of

change

of

correction

is

proportional

to

the

error.

In the

reverse

position

of

zero

stroke

bias

valve

363

with

valve spool

364

in

the

central

blocking

position

shown,

the

pump

ring

370

is

slightly

displaced

from

null

(N)

or

zero

stroke

position

to

a

reverse

bias

(RB)

posi

tion

(FIGS.

3A

and

4)

having

very

low

reverse

or

nega

tive

displacement,

In

response

to

a

displacement

posi

tion

error

due

to

higher

or

lower

displacement

from

reverse

bias

(RB)

position,

the

zero

stroke

bias

valve

363

respectively

provides

reverse

return

signal

in

re

verse

return

line

383

or

forward

return

signal

in

lst

forward

return

line

384,

functioning

as

a

reverse

ad

vance

signal,

for

correction.

In the

forward

position,

in

response

to

forward

signal

supplied

by

forward

signal

line

288,

the

valve

sleeve

366

is

moved

to

the

left

in

FIG.

3A

to

forward

position;

and

when

valve

spool

364

is

in

a

similar

central

blocking

position

relative

to

reverse

and

lst

forward

return ports

371

and

372,

the

pump

ring

370

is

in

forward

bias

(FB)

position

(FIGS.

3A

and

4),

displaced

a

little

from

null

(N)

position,

to

a

very

low

forward

or

positive

displace

ment

position.

On

displacement

error

from

forward

bias

(PB)

position

to

higher

or

lower

displacement

positions,

zero

stroke

bias

valve

363

respectively

provides

for

ward

return

pressure

in

lst

forward

return

line

384

or

reverse

return

signal

pressure,

acting

as

forward

ad

vance

signal

pressure

in

reverse

return

line

383.

This

arrangement

provides

a

damped

minimum

displacement

control

to

prevent hunting

of

the

displacement

control

by

placing

the hydrostatic

pump,

under

low

load

pro

viding

creep

torque

and

conditioning

the

propulsion

20

25

30

35

45

50

60

65

drive

13

in

forward

or

reverse

manual

range

for

imme

diate

forward

lst

ratio

range

or

reverse

ratio

range

drive

in

response

to

torque

demand.

2-3-2

SHIFT

SIGNAL

VALVE

The

2-3-2

shift

signal

valve

386

has

a

spool

387

having

two

equal-diameter

lands

a

and

b

slidable

in

a

bore 388

which

is

in

valve

body

169

and

is

vented

at

both

ends.

Linkage

389,

which

is

like

linkage

367

of

zero

stroke

bias

valve

363

and

has

adjustment

device

390,

connects

spool

387

to

pump

ring

370

for

proportional

movement.

The

forward

signal

line

288

is

always

connected

to

the

space

in

bore

388

between

lands a

and

b

of

spool

387.

The

2-3-2

shift

signal

line

391

is

connected

to

its

port

392,

and

when

pump

ring

370

and

valve

spool

387

are

not

in

2-3-2

shift

position

as

shown

(FIG,

3A),

2-3-2

shift

signal

line

391

is

connected

by

its

port

392

around

land

a

of

spool

387

to

exhaust

line

393

connected

to

bore

388

beyond

land

a of

spool

387

for

exhaust.

When

pump

ring

370

and

spool

387

are

in

the

2-3-2

shift

position,

land

a of

spool

387

closes

exhaust

line

393

and

connects

forward

signal

line

288

to

supply

2-3-2

shift

signal

line

391.

~

l-2-l

SHIFT

SIGNAL

VALVE

The

l-2-l

shift

signal

valve

396

has

a valve

spool

397

having

two

equal-diameter

lands

a

and

b

slidable

in

bore

398

and

connected

by

linkage

399,

like

the

above

link

age

367,

to

motor

ring

401.

Bore

398

is

vented

at

both

ends.

When

motor

ring

401

and

thus

valve

spool

397

(as

shown

in

FIG.

3A)

of

l-2-l

shift

signal

valve

396

are

in

other

than

l-2-l

shift

position,

l-2-l

shift

signal

valve

396

connects

l-2-l

shift

signal

line

402

to

exhaust

403.

When

motor

ring

401

and

l-2-l

shift

signal

valve

396

are

in

l-2-l

shift

position,

l-2-l

shift

signal

valve

396

con

nects

forward

signal

line

288

to

supply

l-2-l

shift

signal

line

402.

ZERO

STROKE

INDICATOR

VALVE

The

zero

stroke

indicator

valve

132

(FIG.

3D)

has

a

spool

407

having

two

equal-diameter

lands a

and

b

slidable

in

a

bore

408

vented

at

both

ends

thereof

by

1st

and

2nd

exhausts

413

and

413'.

Linkage

409,

like

linkage

367,

connects

spool

407

to

pump

ring

370.

Mainline

112

is

always

connected

to

bore 408

between

lands a

and

b

of

spool

407

and

is

blocked

so there

is

only

leakage

flow

to

lst

and

2nd

ports

410

and

410’

in

the

zero or

null

(N)

stroke

position

of

spool

407

as

shown

in

FIG. 3D.

This

leakage

flow

past

lands a

and

b

of

spool

407,

respec

tively,

to

lst

and 2nd

ports

410

and

410’

is

permitted

to

escape

at

low

pressure

via

lst

and

2nd

restricted

pas

sages

412

and

412’

and

extending

respectively

from

1st

and

2nd

ports

410

and

410'

beyond

lands a

and

b

of

spool

407

and

returning

to

bore

408

for

exhaust

by

exhausts

413

and

413’

at

opposite

ends of

bore

408.

This

arrangement

reduces

leakage

and

the

low

pressure

pro

duced

in

zero

stroke feed

lines

411

and

411’

is

not

signif

want.

When

pump

ring

370

moves

from

zero

stroke

or

null

(N)

position

in

either

direction,

spool

407

moves

to

connect

mainline

112

to

selectively

supply

either

of

lst

or

2nd

ports

410

or

410’

and

lst

and 2nd

zero

stroke

feed

lines

411

and

411’.

After

movement

of

ring

370

in

one

direction

from

zero

stroke

position

(N),

with

land

a

of

spool

407

moving

to

connect

mainline

112

to

lst

port

410

and

lst

zero

stroke

feed

line

411

and

lst

restricted

passage

412,

with

small

further

movement

land

a

of

spool

407

blocks

the

connection

of

1st

restricted

passage

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