HP 2500C Series - Manual (Page 130)

Functional Overview 6-10
Paper Paths and Components
Ramp Drive
Ramps are driven by Stepper motor (Bi-polar) through gear train. Each ramp has rack
tooth profile and individual pinion fitted in a shaft engages with rack tooth. The ramps
can be moved in both directions (extended and withdrawn). Ramps are stopped in both
directions mechanically by Platen surfaces. In the forward direction, ramps are stopped
by stopper (snapped to it ) hitting the Platen surface. In the reverse direction, projection
in the ramp hits the Platen surface.
In reverse direction, projection in the ramp hits the Platen surface.
Output roller
(on platen)
Stopper
Gear-ramp
(on platen)
Stopper
Ramp stopper
Ramp
Platen
Ramp slipping mechanism
Slipping arrangement is provided for the ramps. During Printer initialization as well as
during resetting after Elec. Power disruption we need to bring the ramps back to their
home position (withdrawn condition) as we will not know their current position. To
achieve this ramps have to be overrun but at the same time the drive to the ramps should
be cut-off once they have reached their home position. Axially loaded compression
spring provides frictional force (400gm) to the slip-gear which transmits motion from the
drive shaft to the ramp-gear.
In case the resistance force from the ramps increases (due to stoppage) more than
400 gms,the spring compresses further and thereby slip-gear starts slipping.
Force required to stall/ hold the ramp for slipping : 175-275 gm
(measured on the face of the ramp i.e;
opposite to the direction of ramp movement )