Service manual

ManualsBrandsSCORPION ManualsSnowmobiles1975 Brut

SERVICE

MANUAL-

1975

SCORPION

BRUT

DRIVE SYSTEM

Functional

Description:

The

main

elements

included

in

this

system

ore:

1.

Drive

Clutch

2.

Drive

Belt

3.

Driven

Clutch

4.

Chain

Case

with

sprockets,

chain

and

chain

tensioners.

5.

Drive

shaft

with

track

drive

sprockets.

The

power

from

the

engine

is

transmitted

through

this

system

to

the

track

in

sequence

of

elements

listed

above

to

propel

the

machine.

The

drive

clutch,

belt

and

driven

clutch

serve

as

a

torque

converter.

The

torque

converter

on

the

snowmobile

"down

shifts"

to

a

lower

ratio

as

the

track

load

in-

creases

as

readily

as

it

"up

shifts"

when

the

track

load

decreases.

To

accomplish

the

automatic

shifting,

the

movable

sheave

of

the

driven

clutch

is

fitted

with

a

helical

romp

which

is

guided

by

a

follower.

This

sheave

is

con-

trolled

by

a

spring

pre-stressed

in

torsion

and

compression

to

hold

the

sheaves

together

at

the

maximum

pitch

diameter.

The

drive

clutch

cover

has

a

set

of

centrifugal

weights

and

helical

romps.

The

drive

movable

contains

a

mating

set

of

romps

(followers).

A

spring

automatically

positions

the

movable

drive

clutch

at

the

minimum

pitch

under

zero

and

idle

speed

conditions

.

Under

acceleration,

the

torque

from

the

engine

is

greater

than

the

demand

from

the

track.

As

RPM

increases,

the

weight

arms

move

to

force

the

movable

in

(away

from

the

cover).

At

the

some

time,

the

belt

tension

and

belt

friction

on

the

movable

sheave

results

in

a

relative

rotational

motion

between

the

cover

and

the

movable

such

that

the

cam

action

also

forces

movable

away

from

the

cover.

The

wedging

action

of

the

drive

sheaves

forces

the

belt

outward

in

the

driven

clutch.

Belt

tension

and

wedging

action

are

greater

than

spring

forces

of

the

driven

clutch

and

the

sheave

faces

are

wedged

open

against

the

helical

cam.

This

ac-

tion

winds

up

and

compresses

the

spring.

Under

steady

running,

all

forces

are

balanced

and

the

belt

chooses

a

ratio

at

which

this

balance

exists.

Under

deceleration,

the

driven

stationary

stalls

slightly.

The

belt

tension

and

friction

on

the

driven

movable

plus

spring

torsion,

moves

the

movable

along

the

ramp,

closing

it

and

forcing

the

belt

out

to

a

greater

pitch

diameter.

This

ac

-

tion

increases

belt

tension.

Wedging

action

opens

the

drive

movable

against

the

weights

down

the

ramps

to

a

new

lower

pitch

diameter

for

the

drive

clutch

until

forces

are

again

equalized.

4-2

)