With the acceleration of urbanization, fire engines are widely used in fire fighting of urban buildings. Fire trucks are relatively complex in structure and require extremely high safety. Therefore , in this paper , the common faults of fire engines are taken as the research objects. Firstly, the overall structure of fire engines is summarized . Then, the common failures of fire vehicles and the troubleshooting steps are discussed.
First, the basic composition of fire engines
( I) Truck Chassis
( B) Power Transmission System (Power Take-off)
( III) Tanks
( four) water pump
( 5) Firefighting pipelines (including on-board guns)
( VI) Electrical Equipment
Second, common failures and diagnostic procedures for fire vehicles
( I) Chassis section
1. Diesel engine oil discharge air
2. The generator does not generate electricity diagnosis and troubleshooting
3. Check adjustment of clutch free stroke
4. Inspection and adjustment of brake shoe
5 gearbox (gear pull line is more common)
( B) Power take-off troubleshooting steps
This section focuses on the analysis of vehicle faults using a combination of electromagnetic and pneumatic valves. Symptoms: Depress the clutch pedal, press the power take off button, release the clutch pedal, the pump can not operate normally.
First, the basic composition of fire engines
( I) Truck Chassis
( B) Power Transmission System (Power Take-off)
( III) Tanks
( four) water pump
( 5) Firefighting pipelines (including on-board guns)
( VI) Electrical Equipment
Second, common failures and diagnostic procedures for fire vehicles
( I) Chassis section
1. Diesel engine oil discharge air
2. The generator does not generate electricity diagnosis and troubleshooting
3. Check adjustment of clutch free stroke
4. Inspection and adjustment of brake shoe
5 gearbox (gear pull line is more common)
( B) Power take-off troubleshooting steps
This section focuses on the analysis of vehicle faults using a combination of electromagnetic and pneumatic valves. Symptoms: Depress the clutch pedal, press the power take off button, release the clutch pedal, the pump can not operate normally.
2. Several kinds of power sources of the current vehicle fire pump diversion device
(1) Belt drive. Rely on pump gearbox belt drive.
(2) V DC motor drive. (mainly represented by U.S. Dali and HELL series scraper vacuum pumps)
(3) Pump shaft direct drive. (New type of piston water diversion device independently developed by Jetta)
( C) Several types of control methods for the current vehicle fire pump diversion devices
1. Mechanical lever operation. (As represented by Xi'an Huayu, a mechanical lever is used to operate the water diversion valve, and the steel wire rope on the lever drives the vacuum pump to turn the wall of the vacuum pump to tighten the vacuum pump driving belt to drive the piston vacuum pump to operate. After the water diversion, the pressure water pushes the spring to turn the wall and overcomes. The spring force breaks the belt and stops the water diversion work.)
2. Use electromagnetic clutch transmission. (The button on the operation panel turns on the power of the electromagnetic clutch , and the electromagnetic clutch generates electromagnetic force to drive the vacuum pump to run. The water pressure at the outlet after the water diversion is the control switch automatically cuts off the power and stops the electromagnetic clutch automatically.)
3. Directly open the diversion switch. (At the same time when the vacuum line valve is turned on, connect the 24 V DC power supply, and the vacuum pump will run the air in the pumping chamber at high speed. After the water diversion is completed, release the water diversion switch.)
( 4) Common Faults and Analysis Exclusion Steps
The point of failure is the part that transfers kinetic energy. (Ie: drive belt, or power supply. Generally speaking, the vacuum pump does not work, there is no kinetic energy to it) is mainly represented by the operation of the water switch or button. The vacuum pump does not run and the vacuum gauge does not indicate vacuum. The inspection and analysis steps are personally considered as follows: Mechanical wall-to-wall type: Observe the wall motion of the vacuum pump and the tightness of the belt. The cable length can be adjusted appropriately. With the vacuum line valve fully open, the vacuum pump drive belt tension is appropriate (do not skid properly). It should be noted here that the two end surfaces of the drive belt are on the same end surface, otherwise, it is easy for the belt to disengage, slip, and squeak.
1. Electromagnetic clutch type: First check whether the fuse is blown.
Use the test light at the electromagnetic clutch connection to check if there is electricity. When there is electricity, use a screwdriver to approach the electromagnetic clutch. If there is no strong magnetic force, the electromagnetic clutch is damaged. If there is no electricity at the electromagnetic clutch, check whether the pressure sensor switch is intact (you can test the terminals at both ends of the switch respectively. If there is no electricity at the side of the power supply on the power feeding side, as long as the pressure gauge shows no pressure, it is the sensor. Damage) If both terminals of the sensor are dead, check the connection of the sewer switch (you can test the terminals at both ends of the switch separately. If there is no electricity on the side with electricity on the power feeding side, the directional water switch is damaged). If both ends are dead, check if the line is short-circuited or consider replacing the new water supply line. DC motor type: If pull pump switch vacuum pump does not work, you can use test light to check the terminal on the vacuum pump. The main power line (coarse) must have electricity. Whether there is electricity in the relay circuit, under normal circumstances, relay failure is more common. Of course, there will be a motor burnout failure (mainly due to motor water or improper operation)
2. Vacuum pump
Piston type water diversion device: (vacuum pump can rotate, mainly) for the aging of the seal body inside the pump body caused by the leakage of air to affect the degree of vacuum, the pump body can be replaced to replace a new set of seals. Vacuum pump does not move, mostly lack of oil leads to internal burn, need to be decomposed after the repair or replacement as the case
Water ring water diversion device: (usually seen as: water shortage in small tanks, pipeline blockage, etc.. There is also a long time model pump casing due to long-term corrosion or dirt too much affect the water absorption efficiency)
Squeegee type diversion device: (mostly blade damage, but also severe wear and oil ablation. Replaceable blade can increase lubrication)
( five) fire line failure
This section mainly explains the analysis and troubleshooting of common failures of pneumatic valves. Failure mainly manifested as pressing a valve button, the valve can not normally open and close! First, check whether the barometer reading of the vehicle is 8 Kpa. Then, use a pencil to measure whether the solenoid valve is energized. If there is no electricity, check if there is an open circuit between the fuse- switch- solenoid valve. If it is energized, check if the solenoid valve is in good condition (test of the valve can be used). Note: The fault may also be due to cylinder wear or stuck, resulting in the cylinder being too small to overcome the resistance to open or close. Therefore, the valves of the water pump pipeline should be opened and closed several times a day to prevent seizure and affect the fire fighting operations.
( VI) Electrical Equipment
The main points of failure of the vehicle electrical equipment are as follows:
1. Poor Ground. As the body is made of aluminum, it is glued. Reduced conductivity. Pay attention to checking the condition of the vehicle's ground.
2. Line aging line, because fire-fighting vehicles are easy to water. Easy to cause long-term wet end of the thread. Accelerated aging leads to poor contact.
Third, the conclusion
With the continuous development of urbanization and the ever-increasing urban floors, fire engines have emerged. The structure of the fire trucks is complex, and the requirements for safety levels are even higher. At present, research on truck maintenance and trouble shooting is relatively insufficient, based on these circumstances, Taking fire engines as a starting point to explore the whole structure fire engine, then its common faults and maintenance measures to do a study, in order to Current firefighting services provide guidance and reference.
This article from the "Fire Forum", re-edited by China Rescue Equipment Network.
Hebei Charlotte Enterprise Co., Ltd. , https://www.cnscreening.com