Vinten Vision Ped Plus Maintenance Manual page 14

Contents
Telescopic column
8 The telescopic column consists of:
8.1 An outer tube
8.2 An elevation tube
8.3 A tank assembly
Outer tube
9 The outer tube (16)
casting (12) of the skid assembly, where it is secured by the skid clamp (11). The upper end of the tube is
fitted with a clamp (18) which secures the elevation tube of the telescopic column. Three leg ties radiate from
the upper part of the tube (17). These leg ties engage with the foot supports
the pedestal its strength and stability.
10 The pedestal is supplied with a retaining strap
telescopic column during transportation and storage.
Elevation tube
11 The elevation tube
relative to the outer tube defines the working height of the pedestal. Once set at the required height, the
elevation tube is secured by tightening the bottom clamp (18).
12 The upper end of the tube is fitted with three sets of rollers which guide the tank assembly and a clamp
(19) which secures the tank assembly in position. The lower end is closed by an end plate to which the tank
assembly piston rod is secured.
Tank assembly
1. The tank assembly
elements: the tank, the control valve and the ram cylinder. The outer wall of the tank has three machined
longitudinal flats, which engage with the rollers in the elevation tube
movement. The control valve
tank.
2. The tank is fitted with a pressure relief valve at its base, which is set at 11.0 bar (160 psi) to prevent
over-pressurization.
3. The control valve
it provides direct connection between the ram cylinder and the tank. In the 'Pump' position the control valve
closes the connection between the ram cylinder and the tank and air compressed in the ram cylinder reaches
the tank through a non-return valve to raise the pressure in the pneumatic system. An intermediate position
mid-way between 'Pump' and 'Work' provides a restricted connection between the tank and the ram cylinder
so that the pressure in the ram cylinder may rise gradually to tank pressure. When set to the 'Bleed' position
the control valve provides a restricted vent from the tank to atmosphere to reduce tank pressure. During
normal operation of the pedestal, the control valve is set to the 'Work' position and permits no further alteration
of pressure.
4. The ram cylinder provides the counterbalance effort for the column and payload. It also acts as a pump
to pressurize the pneumatic system. The base of the piston rod is fixed in the elevation tube. When the control
forms the bottom section of the telescopic column. Its lower end fits into the centre
(5) forms the middle section of the telescopic column. The positioning of this tube
(4) forms the uppermost section of the telescopic column and comprises three main
(2) is an integral part of the tank top plate. The ram cylinder is housed within the
(2) selects the mode of operation of the ram cylinder. When set to the 'Work' position
First
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(7)
(6) to secure the leg ties to the outer tube of the
(5) to guide it and to prevent rotational
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on the skid assembly to give
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