Offloading and positioning
Even small machines that are delivered in one unit require lifting equipment to offload, transport and position them in the pit. Forty-eight-inch roll machines or larger units may have to be positioned in already built or partly completed chambers; therefore, the installation will often require specialist equipment and contractors to lift and manoeuvre the machine in a building area of limited headroom and limited floor access as in the case of lined climatic chambers. It is a project phase that is used as an example in the ‘Project timing chart’ section of Chapter 1, which is recommended reading.
Tyre burst detectors
On all mileage accumulation rigs and others undertaking prolonged automatic test sequences, there should be some form of detector that can safely shut down the whole system in the event of a tyre deflating. The most common form is a limit switch mounted on a floor stand with a long probe running under the car at its midpoint with limit switches fitted one on each side. Any deflation will cause the vehicle body to drop, shutting down the test in a safe manner.
Cable layout
The general treatment of this subject in Chapter 10 applies in the present case, but special attention should be given to the avoidance of electrical interference from power cables with instrumentation lines. In many cases, all the cables running to the chassis dynamometer will at some point run through plastic tubes set within the concrete of the pit walls and plant room floors. These cable tubes should be allocated to either power or signal and should have a drainage slight fall to the pit. After installation is complete, the tubes can be ‘stopped’ at both ends with acoustic and fire attenuating material.
Loading and emergency brakes
It must be possible to lock the rolls to permit loading and unloading of the vehicle. These consist of either disc brakes fitted to the roll shafts or brake pads applied to the inside surface of one or both rollers. In normal operation these brakes have to be of sufficient power to resist the torques associated with driving the vehicle on and off the rig. Pneumatic or hydraulically powered, they are controlled either by the operational controls (vehicle loading) or by the safety instrumentation (EM stop) and are designed to be normally ‘on’ and require active switching to be off (machine operational).
It is not considered good practice to rely solely on these brakes to bring the rig to rest in the case of an emergency. They should only be used to supplement the braking effort of the main drive system. In addition there must be a well-thought out ‘lock-out’ system to ensure that all personnel are outside restricted areas before start-up, particularly important in large facilities where the operator may not be able to see all areas.
Offloading and positioning
Even small machines that are delivered in one unit require lifting equipment to offload, transport and position them in the pit. Forty-eight-inch roll machines or larger units may have to be positioned in already built or partly completed chambers; therefore, the installation will often require specialist equipment and contractors to lift and manoeuvre the machine in a building area of limited headroom and limited floor access as in the case of lined climatic chambers. It is a project phase that is used as an example in the ‘Project timing chart’ section of Chapter 1, which is recommended reading.
Tyre burst detectors
On all mileage accumulation rigs and others undertaking prolonged automatic test sequences, there should be some form of detector that can safely shut down the whole system in the event of a tyre deflating. The most common form is a limit switch mounted on a floor stand with a long probe running under the car at its midpoint with limit switches fitted one on each side. Any deflation will cause the vehicle body to drop, shutting down the test in a safe manner.
Cable layout
The general treatment of this subject in Chapter 10 applies in the present case, but special attention should be given to the avoidance of electrical interference from power cables with instrumentation lines. In many cases, all the cables running to the chassis dynamometer will at some point run through plastic tubes set within the concrete of the pit walls and plant room floors. These cable tubes should be allocated to either power or signal and should have a drainage slight fall to the pit. After installation is complete, the tubes can be ‘stopped’ at both ends with acoustic and fire attenuating material.
Loading and emergency brakes
It must be possible to lock the rolls to permit loading and unloading of the vehicle. These consist of either disc brakes fitted to the roll shafts or brake pads applied to the inside surface of one or both rollers. In normal operation these brakes have to be of sufficient power to resist the torques associated with driving the vehicle on and off the rig. Pneumatic or hydraulically powered, they are controlled either by the operational controls (vehicle loading) or by the safety instrumentation (EM stop) and are designed to be normally ‘on’ and require active switching to be off (machine operational).
It is not considered good practice to rely solely on these brakes to bring the rig to rest in the case of an emergency. They should only be used to supplement the braking effort of the main drive system. In addition there must be a well-thought out ‘lock-out’ system to ensure that all personnel are outside restricted areas before start-up, particularly important in large facilities where the operator may not be able to see all areas.
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