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 | PARKING
LARGE GOODS VEHICLES SAFELY
Guidance for drivers on coupling and uncoupling large goods vehicles (LGVs)
Introduction
Between 1986 and 1996 HSE inspectors investigated
a total of 24 fatal and serious accidents resulting from bad practice during the
coupling of heavy vehicle combinations. These accidents occurred when: n LGVs
(commonly known as HGVs) moved when the trailer air lines were coupled; and n
the semi-trailer parking brake had not been applied when it was parked. Accidents
will continue to happen unless the simple precautions described in this leaflet
are taken. |
| It is common practice
for LGV drivers to leave the tractor unit with its
engine running and the parking brake not applied
when coupling or uncoupling the air lines to the
semi-trailer. This is unsafe practice. The accidents
do not necessarily reflect inexperience. One |
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casualty had 20 years’
experience as a driver. Although this advice applies to
LGVs with semitrailers, it applies equally to other vehicle
combinations with similar braking systems.
1 Accidents when coupling the air lines Accidents
occur during coupling up because it is common practice
for trailers to be parked on the emergency brake by disconnecting
the emergency airline (‘dropping the red line’) rather
than by applying the trailer parking brake.
This is unsafe practice because connecting the air lines
to a parked semi-trailer, when its parking brake is not
applied, releases its brakes under air pressure and the
vehicle combination can then move, particularly on an
incline.
This unsafe practice has resulted in drivers being:
• run over by the moving vehicle; or
• crushed between the vehicle and another object,
often as they attempt to get into the moving tractor
cab to apply the parking brake.
Accidents due to parked semi-trailers moving
Drivers and others have been injured when they were hit
or run over by semi-trailers which were left parked.
These accidents occurred because the semi-trailer ran
away or moved on a slope because its parking brake was
not applied when it was disconnected from the towing vehicle.
Sometimes movement occurred after the semi-trailer had
been parked for a substantial period of time.
2
It is true that the emergency brakes are applied under
air pressure when the emergency air line is disconnected
from the semi-trailer. However, on trailers with manually
applied (ratchet) parking brakes, and some with spring
brakes, the emergency brakes cannot be relied on as a
parking brake. Air pressure will inevitably leak from
the braking system over time and loss of air pressure
can affect the ability of the emergency brakes to hold
the semi-trailer in its parked position.
Parking on a gradient
A piece of ground may look flat but it only needs a slight
gradient for the vehicle or semi-trailer to move if their
parking brakes are not applied.
Coupling procedure: safety checklist
The vehicle will not move while it is being coupled if
the semi-trailer parking brake is applied. However, when
the semi-trailer parking brake is released the vehicle
can move if the tractor unit parking brake is not applied.
3
Here are the key steps for safe coupling:
• check that the trailer parking brake is applied;
• reverse the tractor unit slowly under the semitrailer
and listen for the locking mechanism to engage;
• check that the fifth wheel locking mechanism is
fully engaged (usually by trying to drive forwards in
a low gear);
• apply the parking brake on the tractor unit;
• visually check the engagement of the fifth wheel
and, depending on the type of mechanism, put on any safety
clip;
• reconnect the air lines (turning on any air taps
that may be fitted to older vehicles) and electrical supplies
to the semi-trailer;
• wind up the semi-trailer landing legs and secure
the handle;
• release the trailer parking brake; and n fit the
number plate, as well as any necessary warning plates,
and check the lights etc.
The procedure for uncoupling is generally the reverse
of the coupling procedure, but always remember to set
the tractor unit parking brake before leaving the cab.
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Also,
before uncoupling check that:
• the ground is firm and level enough to support
both the landing legs; and
• the parking brake is set on the trailer.
After uncoupling check that the landing legs are
not sinking into the surface. |
4
What the law requires
Drivers (including the self-employed) have a responsibility
to take reasonable care of their own health and safety
and the health and safety of other people who may be affected
by their actions.
What the law means to you.
If you couple or uncouple a semi-trailer without applying
the parking brake on the tractor unit or leave a semi-trailer
parked without its parking brake applied, you are breaking
health and safety law and may be responsible for killing
or injuring yourself or someone else.
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