Fork Working - Marzocchi MAGNUM 45 Bedienungsanleitung

4
A
COMPRESSION - COMPRESSIONE -
COMPRESSION - EINFEDERUNG
1 pos. 2 pos.
4
5
3
1
6
2
7
B
REBOUND - ESTENSIONE -
EXTENSION - AUSFEDERUNG
3 pos.
4
5
3
1
6
2
7

FORK WORKING

A spring is accommodated in the upper section of each fork leg that provides for the fork static load. Using
springs with different hardness or pre-load sleeves with different lengths will change fork response with no
need to alter the setting of the hydraulic damping system. This considered, let us know take a closer look at the
different valves that are the key components of the hydraulic damping system of this specialized fork. In order
to give a better explanation on how the suspensions work, the moving parts (halftone) are different from the
parts fixed to the cycle frame; any oil flowing or movement in the different working stages is represented by
means of arrows. Each fork leg is formed by a cartridge (1, Fig. A) with an inner pumping element (2, Fig. A)
secured to the upper plug (4, Fig. A) of the stanchion tube by means of a rod (3, Fig. A). A screw adjuster
located on the plug operates an inner push-rod (5) that in turn displaces a conical pin (6) placed right on top
of the pumping element of each fork leg. This system prevents the fluid from flowing from the bottom up to the
fork leg top, as was the case with older series models, as the parts found in that area have lesser lubrication or
cooling requirements. What this adjuster does is determine the size of the porting area through which the fluid
flows in and out of the cartridge. The pumping element is equipped with washers which bypass the oil
flowing. The structural arrangement of the pumping elements is characterized by a separate multivalve
system for each fork leg which allows all the fork working parameters to be kept under control in the
different use conditions and, at the same time, allows an aimed intervention without changing the existing
configuration, but simply changing the area of each individual oil porting. This system also avoids any
dangerous cavitation effect often occurring in forks where the fluid flows through one or two critical points.
Let's see what happens in a (L.H.) COMPRESSION leg if riding on an uneven track (1 pos., Fig. A):
- the oil in the damper cartridge is pushed downwards by the pumping element and flows through the slot
in the control cylinder without any problem. Thanks to the portings in the upper area of the hydraulic
cartridge, this fluids mixes with that flowing out of the rod bore near the conical pin;
- under this condition he washers on the pumping element piston are still completely closed and the fluid
volume flowing through the adjustment pin is not important with respect to the fluid flowing through the
slot;
- for this reason, the result will be a not very braked fork able to absorb the small unevenesses of the track.
Let's see what happens in presence of some remarkable obstacles, such as a series of bumps (2 pos., Fig.
A):
- a big part of the damper rod goes into the damper cartridge so that the pumping element moves up to mid-
length of the slot and lets a smaller amount of oil into the control cylinder;
- the oil pressure is not enough to wear down the resistance of the pumping element washers and, at this
stage, the position of the conical pin of the adjustment unit shutting the fluid flowing through the inner
bore of the pumping element plays a major role;
- in this way a more braking response of the fork is obtained, above all dependent upon the smaller outlet
area of the fluid and the adjustment unit position.
Now let's see what happens inside the leg during a violent compression caused by a big obstacle
(3 pos., Fig. A):
- the pumping element goes beyond the fluid outlet slot of the control cylinder and shuts it down, so that oil
pressure opens the bottom washers and overcomes the upper counter spring of the piston. Oil fills the
chamber on top of the pumping element to compensate for the space taken up by the rod inside the cartridge;
- at this point, both the porting area for the fluid to flow through the pin valve controlled by the upper adjuster
and the resistance offered by the set of bottom washers of the foot valve (7) play a major role;
- the result will be a very braked fork and this condition can be increased or decreased by means of the
adjustment unit.
In the (R.H.) REBOUND leg the foot valve (6, Fig. B) is very important. The foot valve is fixed to the bottom end
of the slider. It has a set of spring washers at the bottom and a single washer with a counter spring at the top
end. This valve has the purpose of metering the oil filling the damper cartridge.
Let's see what happens in a REBOUND leg (Fig. B) after a sharp compression;
- the pumping unit is returned by the spring power and the oil in the upper chamber can flow into the lower
chamber, thus wearing down the piston washers resistance;
- the oil also flows through the hole on the rod bottom. This oil flowing is adjusted by means of the upper
adjustment unit which, at this point, is all-important;
- under the above conditions, the foot valve takes fluid from outside the cartridge and fills it into the chamber
under the pumping element. Oil flows easily through the foot valve as it only needs to overcome the resistance
offered by the small counter spring.
US UK 5