Public Service Vehicle (PSV) Workshop

Transcription

1 Public Service Vehicle (PSV) Workshop Education Handout (V3 10/01/10) The UKRO authorises the use of the educational information contained within this document, however reference must be given to UKRO with the use of the UKRO logo

2 1. Introduction With the increase in road use and the increasing population within the UK a rise in the number of coaches and public service vehicles has been seen. For the operational firefighter incident complexities involving such vehicles range from entrapments, firefighting, stability, constructions and access. This document aims to give firefighters an overview of modern PSV constructions and provide information on stability, glass, fuel and access issues. The information contained within this handout as part of the workshop is a small amount of the information which is being made available through the UKRO and its partnership organisations. Should you wish to receive further information please contact Dick Dawson who is part of the UKRO Education Committee (ddawson@ukro.org) 2. New Technologies and Construction Most modern buses (2002 onwards) are of modular construction and are not built upon a full traditional chassis, normally a front/ rear sub frame design. Glass panels form part of the vehicle structure and may be bonded, where as front and rear windscreens can still be held in by the more traditional rubber seal, which can facilitate easy access if necessary. Typical examples of these vehicles are: Wrights Gemini (body) on Volvo chassis Dennis Alexander (body) on Dennis chassis The body frame and floor frame is built from square steel tube section and pressed panelling/ sections, body panels are made from galvanised sheet steel or aluminium (approx 1.0mm) with fibre glass reinforced plastic (FRP) mouldings. Often the front and rear vehicle facings are of FRP construction. Compromising any pillars or part of the panels will be detrimental to the structural integrity and should be avoided wherever possible, unless suitable structural stabilisation is employed. Page 2

3 Square Construction of PSV Vehicle As with traditional extrication standards when examination of a vehicle structure takes place, it is necessary for a peel and reveal strategy. As the pictures below show, the internal panels within PSV are lined with various types of insulation materials and covered with FRP panelling Page 3

4 A useful guide for firefighters wishing to stabilise and lift PSV s in particular double decker buses, we have the following approximate weights and dimensions: total height: 4.39m total weight: 12,500kg front axle weight: 3,500kg rear axle weight: 9,000kg Engine stop and power isolation The engine can be stopped via an emergency stop button located at the rear under a lift up panel and will be clearly labelled. Operation of this button will stop the engine but will leave the ancillary power on. Emergency Engine Stop There is an isolation switch located in the driver s cabin which is clearly marked and housed under an orange safety cover (other manufacturers will employ a similar system). This switch will stop the engine and turn off all ancillary power. When the engine is stopped, air will leave the system and the spring brake will be activated. The vehicle will also lower as the air leaves the air suspension system. Driver s emergency isolation switch Page 4

5 Batteries and isolation switch Battery Tray in the Extended The batteries can be isolated via a remote switch (these will vary depending on manufacturer). The electrical system is 24 volts. Fuel Tank Locations Located on the front axle either on the centre line inboard or behind an outer body panel, plastic construction on more modern vehicles. Capacity 180 litres (city bus) up to 1,000 litres (coach) Page 5

6 Stabilisation Considerations It is important to consider the construction of the vehicle when determining suitable jacking/lift points and areas for blocking for stabilisation. The modern buses are not built on a full traditional chassis, and consist of a front and rear sub frame. When jacking/lifting, it is possible that the chassis will distort causing stressed glass panels to break. This is more likely to occur in double-decker vehicle. Crews must be aware of the potential for glass fragments to fall from both the upper and lower decks. PPE must be worn and protection provided to casualties. The sub-frames should be used as jacking/lift points whenever possible to minimise the risk of the above Modern vehicle, low chassis Page 6

7 Older vehicle, traditional chassis Depending on vehicle manufacturer there may be markings on the body to indicate the position of lifting points. Such points are substantial and can be utilised for stabilisation and lifting. Page 7

8 Drivers Seat There are two types of seat in current use in PSV vehicles, the mechanical and the pneumatic (air seat) which by far the most common. Both use a cantilever type framework with either a mechanical spring/ damper or a pneumatic air bag as the suspension component. The pneumatic seat is supplied via the vehicles auxiliary air supply circuit at a pressure up to10 bar. Electric Seat Adjustment Controls (see next page for more information) Cantilever / scissor frame Air bag / spring Damper Unit In a collision scenario the seats movement needs to be managed by inserting a block/ wedge into the lower framework, lowering the seat under control using the controls, and then disconnecting the seats air supply. Page 8

9 Drivers Seat Controls A correct understanding of the controls on PSV drivers seats can ensure that the actions taken by firefighters result in anticipated results. Additionally, this understanding will allow a greater number of options for firefighters planning their rescue. Damper Control Back Incline Control Seat Height Adjustment Control Swab Tilt Control Air Dump Control The Damper Control enables the driver to adjust the level of damping available on the seat. This reduces the amount of rebound from the air seat. The Swab Tilt Control allows the angle of the seat base to be adjusted to suit the driver. The control of primary importance is the Air Dump Control button. Although shown here in red, this is not always the case. This can be used to remove the air from the airbag under the seat and will allow the seat to drop down. This would be used in conjunction with a wedge to stabilise the drivers seat. A prefered method which provides additional progressive control when lowering the seat, is the use of the seat height adjustment control button. Page 9

10 Brakes Vehicles are equipped with a full air braking system, which is supplied with compressed air from an engine mounted compressor and stored in steel storage tanks mounted on the chassis. The handbrake is mechanical (spring brake) with a manual wind off. When the engine is not running, air will leave the system and the spring brake will operate. It will not be possible to winch a bus with the spring brake applied, therefore early consideration should be given to requesting specialist assistance. Spring brake chamber (handbrake shown in wound off position) In exceptional circumstances it may be necessary to move the vehicle after the engine has been switched off and the spring brake has been applied. The spring brake can be manually wound off utilising a 24mm spanner. On some vehicles, access to the spring brake can be gained via an interior panel over the rear wheel arch. Spring brakes are only fitted to the rear. Access Panel to Spring Brake When activated, the parking brake lever (Handbrake) will lock in the ON position. To release the parking brakes, the release collar needs to be lifted before the lever can be operated. If the parking brake lever is not locked in position the parking brake should be considered off. In the event of a PSV rescue or collision at the earliest stages the vehicles parking brake should be considered. Release Collar Repeated operation of the drivers foot valve or manual draining of the vehicles air tanks will bring on the parking brake automatically if access to the parking brake lever is restricted. Page 10

11 Suspension The suspension is provided by means of air bags front and rear, with additional semi-leaf springs at the rear. The system is supplied as in the air brake system from a storage tank, it is controlled electronically via a chassis mounted levelling valve which constantly adjusts suspension ride height according to passenger load. The driver has dashboard controls to facilitate Kneeling, where the bus s ride height can be lowered to assist elderly and disabled passengers, the vehicle may also have a designated lifting step for wheel chair customers. Drivers main control panel, including air suspension. The driver may well also have a control to raise the vehicle on its suspension, this may prove useful when attending an incident where a person has been run over etc. Lifting Step Note: The vehicle must be stabilised before firefighters attempt a rescue under an air suspended body, should an air bag fail the vehicles ride height will drop without warning. Suspension Air Bag Page 11

12 Use sub frame for jacking points Suspension Guidelines Remove ignition key and operate the drivers emergency isolation switch prior to operations. Failure to do so may result in the air suspension system compensating for movements caused by air leaks or jacking and/or stabilizing measures. When the engine is not running, air pressure will reduce within the airbags causing the bus to lower. Attention to the possibility of the vehicle lowering must be given whilst correct stabilisation procedures are followed. An older standard bus with no kneeling mechanism will have much greater ground clearance of approximately 350mm. Page 12

13 Emergency Exits Emergency exits are located at the off side rear, and the rear window of the upper deck. The upper deck emergency window is hinged at the top and opens upwards; it should be noted that there is no stay to maintain the window in the open position. Side Emergency Exit Rear Emergency Exit In some circumstances, the emergency exits will not be available or deemed inadequate to the situation; therefore, consideration will be given to the removal of glass panels for space creation. In the main glazing is toughened across the sides and rear, and usually bonded in on new coach s/ busses. The front windscreen tends to be held in by a traditional rubber seal. Also a point of interest is the drivers side sliding window is also rubber sealed, thus making glass removal quicker and cleaner to the experienced firefighter. Glass now forms part of the overall strengthening of the vehicle body, and stabilisation needs to be considered if especially side glass is removed. Page 13