The Hydraulic generator designed and developed by UK Generators
Limited is a universal onboard generator option for the powered
access industry. After many years of research and development
and continuous product refinement, we have now introduced
the MK3 unit. The unit consists of several key components
to ensure that it is compatible with the majority of engine
driven access machinery.
So how does it work?
Access platforms all produce hydraulic flow, which makes
them go up, down, drives them forward and back as well as
powers the steering, cage rotation etc. What the hydraulic
generator does is to tap into this flow to provide hydraulic
flow to the integral gear motor of the generator. The complication
is that the flow from the platforms hydraulic circuit does
not always match the needs of the generator, so we have to
regulate the flow. Incorporating a pressure compensated
flow control valve does this. For example, if our platform
flow rate is 60 litres per minute and our generator only
requires 26 litres, we regulate the amount of flow that is
supplied to the generators gear motor by taking the full
60 litres into our manifold and utilising only the 26 litres
we need. The remaining 34 litres is returned to tank
automatically through the flow regulator and ‘return
to tank’ line. This provides the gear motor with a
constant flow ensuring that the generator operates at the
correct speed to provide the voltage and frequency required
to power the electrical equipment being utilised. It’s
that simple.
However, if we send the hydraulic flow required by the platform
through the generator, the platform will no longer function
properly. To overcome this we have incorporated a directional
valve, which, when connected to a generator on/off switch,
will send the hydraulic flow to the generator gear motor
only when the generator is switched to the on position. When
switched off, flow continues as normal to supply the platform
functions.
On Platforms which incorporate fixed displacement gear pumps
producing fixed flow rates at idle and operational speed,
we could have 30 litres per minute at idle speed and 80 litres
at full speed. In this instance we turn the platform on and
switch on the generator. Swash pumps however produce variable
flow rates according to the function called for: for example
the flow rate for the cage rotation function will be considerably
less that than for raising the platform and the steering
will need less than raising but more than cage rotation.
When no function is being called for there is no flow at
all, so if we energise our directional valve at this time,
it simply won’t work. So we then have to not only energise
the directional valve but also influence a function that
will provide the flow required simultaneously by installing
a relay on the function control. This means that when the
generator is switched on, the platform believes that a function
is being called at the same time as energising the directional
valve, this means that flow is generated and sent to the
gear motor and the unit operates accordingly. When the generator
is switch off the function is disabled and the directional
valve de-energised and the platform returns to it’s
normal idle state.
For additional security we have added a safety feature by
incorporating an adjustable pressure relief valve into the
valve block. This protects the platform hydraulic system
in the event of a failure within the generator system. For
example if the generator gear motor seizes, this will create
back pressure blowing the relief valve and sending all flow
back to tank.
All of these component parts are contained within one compact
unit, with 3 ports: P1 main pressure in supply, P2 main pressure
supply generator bypass and T1 return to tank. |
