Finn Bark Blower BB1216, Operator Instructions And Parts Manual

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ing four subsystems, all of which contribute to efficient material flow:
SUBSYSTEM 1: MATERIAL HANDLING GROUP
The four major components of the material handling group are the blower, the drag conveyor, the
feed roll, and the airlock.
The blower is a rotary lobe, positive-displacement-type unit having two double-lobe impellers. The
blower is directly driven off the engine flywheel via a flexible coupling. Therefore, whenever the
engine is running, air is being pumped. The blower is equipped with a relief valve, limiting maxi-
mum air pressure to 16 psi (110 kPa), an inlet and outlet silencer for noise attenuation, and an inlet
air filter.
The drag conveyor receives material from the hopper and conveys it to an opening located at
the rear of the hopper where the feed roll is located. The feed roll ensures a uniform feed of bulk
material to the airlock. The drag conveyor is powered by a variable-speed hydraulic motor, which
also powers the feed roll.
The airlock receives the material from the drag conveyor and receives pressurized air from the
blower. Its primary function is to convey the material from the atmospheric air to a sealed cham-
ber where the blower air picks it up and blows it out of the hose. To enable the Bark Blower to
convey fibrous material, the rotary-air-valve housing is equipped with a cutting knife and the vanes
on the rotor are angled and hardened. If any long material should protrude above a vane, it will
be sheared off, before the vane enters the close tolerance of the housing, by a scissor-like action
between the vane and cutting knife. The rotor of the airlock is directly coupled and driven by a bi-
rotational hydraulic motor and gearbox.
SUBSYSTEM 2: HYDRAULIC SYSTEM
Hydraulic power for the Bark Blower is generated by a flow-and-pressure-compensated, load-
sensing pump that is driven off the engine auxiliary drive. This means the pump can measure how
much load is on the hydraulic circuit and will only pump the oil needed to satisfy the demands of
the circuit. The pump receives DTE-13M hydraulic fluid from the 36gal (136L) reservoir through a
service valve and suction hose. It then delivers it to the valve manifold. The manifold is one block
of machined aluminum, equipped with valve cartridges and solenoids that control all functions of
the Bark Blower.
Two pressure gauges at the valve manifold read the valve inlet pressure. These gauges include
the left/rear gauge and the load-sense pressure (right/front gauge). The left/rear gauge should
always read about 300 psi (2,068 kPa) more than the right/front gauge. This 300 psi (2,068 kPa)
difference is called the margin pressure. The margin pressure is a measurement of the pump's
ability to respond to changes in the hydraulic circuit. If the margin pressure is set too high (over
500 psi [3,447 kPa]), the pump will be too sensitive and can become unstable. If the marging
pressure is too low (below 200 psi [1,379 kPa]), the pump can become sluggish and not provide
enough oil flow for the demand. The margin pressure can be adjusted using the lower compensa-
tor-adjustment screw in line with the load-sense hose on the back of the hydraulic pump. The only
time the gauges will not show the margin pressure is when one of the hydraulic circuits has stalled,
as if the floor conveyor somehow became jammed. In this case, both gauges will show the high-
pressure standby of 2,800 psi (19,305 kPa) until the blockage is removed. High-pressure standby
is the maximum pressure the pump will produce. A system relief valve is set for 3,500 psi (24,132
kPa) to protect the system if there is a failure in the pump compensator.