Telescope Fill Tube Control Valve Manifold; Description - Manitowoc Grove RT770E Service Maintenance Manual

HYDRAULIC SYSTEM
TELESCOPE FILL TUBE CONTROL VALVE
MANIFOLD

Description

The Telescope Fill Tube Control Valve Manifold, located on
the turntable, is controlled by the RCL.The Telescope Fill
Tube Control Valve Manifold prevents the first stage (boom
tele sections 2, 3, and 4) from moving when the second
stage (tele section 1) is extending or retracting by
maintaining oil pressure in the fill tube of the first stage. The
Telescope Fill Tube Control Valve Manifold prevents the first
stage from retracting as the second stage extends by first
diverting oil flow it receives from the Brake Charge and CAC
Fan Priority Flow Control Valve to the pressure port of the
Dual Accumulator Charge Valve Manifold by way of a
4.0 gpm priority flow valve (1, Figure 2-32). Excess oil flow
from the flow valve goes to a spring offset, solenoid
controlled, three-way directional control valve (2) that diverts
oil to tank when de-energized. Only when the second stage
is extending will the RCL energize the directional control
valve, which diverts oil to the first stage. This flow of oil to the
1
2
5
Valve Hydraulic Schematic
Item
1 4.0 gpm Priority Flow Valve
2 Three-way Directional Control Valve
3 Check Valve
4 Relief Valve
2-56
4
7
6
Description
Published 11/26/2014, Control # 447-05
first stage is maintained at two pressure settings by a
solenoid controlled relief valve (3). As the second stage
extends, the RCL, based on inputs from the cylinder length
sensing components, will cause the relief valve to maintain a
low pressure (< 100 psi) if the first stage is fully retracted or a
high pressure (2200 psi) if the first stage is fully extended.
Conversely, the Telescope Fill Tube Control Valve Manifold
also prevents the first stage from extending as the second
stage retracts by varying the excess flow it receives from the
first stage at two pressure settings. Oil coming from the first
stage enters the Telescope Fill Tube Control Valve Manifold
and is diverted by way of a check valve (4) to a pilot-
operated, spring returned, two-position, proportional flow
control valve (5) and a solenoid controlled, spring returned,
two-position, proportional flow control valve with manual
override (6). Only when the second stage is retracting will the
RCL energize the flow control valve (7). As the second stage
retracts, the RCL, based on inputs from the cylinder length
sensing components, will cause the solenoid controlled flow
valve to maintain a low pressure (<100 psi) if the first stage is
fully retracted or a high pressure (2200 psi) if the first stage is
fully extended.
1
3
Item
5 Two-Position Proportional Flow Control Valve
6 Two-Position, Proportional Flow Control Valve
7 Flow Control Valve
RT770E
2
3
7
6 FIGURE 2-32
Description
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