1. Understanding and use of hand tools
1. wrench
A hand tool for loading and unloading threaded fasteners such as bolts and nuts.
(1) Open-ended wrench: The most common wrench, also called fake wrench, has a fixed-size opening at one end or both ends for screwing in nuts or bolts of a certain size.
(2) Torx wrench: Both ends have working ends with hexagonal holes or dodecagonal holes, which is suitable for situations where the working space is narrow and ordinary wrenches cannot be used. Comparison between (1) and (2): Compared with the open-ended wrench, the ring wrench has higher strength and is not easy to slip off when used, but it is inconvenient to put on and take off.
(3) Socket wrench: It is composed of multiple sockets with hexagonal holes or dodecagonal holes, and is equipped with various accessories such as handles and connecting rods, especially suitable for tightening bolts or nuts with very narrow positions or deep depressions.
(4) adjustable wrench: The opening width can be adjusted within a certain size range, and bolts or nuts with different specifications can be rotated.
(5) Torque wrench: it can display the torque applied when tightening bolts or nuts; Or when the applied torque reaches a specified value, it will send out a light or sound signal.
(6) Hexagon wrench: An L-shaped hexagonal bar wrench, which is specially used to turn the hexagon screw. Specifications are expressed in hexagonal relative dimensions.
Step 2: screwdriver
A hand tool is used to tighten or loosen slotting machine screws, wood screws and tapping screws of various sizes. Also known as screwdriver, screwdriver and screwdriver. Screwdriver is generally divided into straight, cross, hexagon and flower shape according to the shape of the knife edge at the top of the rotating rod, and the threaded fastener is screwed with the corresponding screw head respectively. Among them, straight and cross are the most commonly used.
3. Hammer and pliers
Hand hammer: A hand tool used to strike or hammer objects. A hammer consists of a hammer head and a handle. The use of hammers is extremely common, and there are many forms and specifications. Common ones are round-headed hammer, claw hammer, split hammer and assorted hammer.
Hand pliers: hand tools used for clamping and fixing workpieces or twisting, bending and cutting metal wires. The pliers are V-shaped, and usually include three parts: handle, pliers cheek and pliers mouth.
Correct selection of hand tools;
1. Choose the priority of the wrench according to the type of work.
I. Socket wrench
B. Torx wrench
C, open-ended wrench
D. adjustable wrench
2. According to the workplace, the tool socket wrench can work in various ways according to the installed handle:
A. Ratchet handle (used in narrow space, but with small twisting distance);
B, sliding handle (fastest);
C. Turn the handle (it can work quickly, but it is difficult to use in a narrow space).
3. Choose tools according to the rotational torque.
A, the longer the handle, the more torque can be obtained with less force;
B, but if the handle is too long, there is a danger of excessive torque, and the bolt may break.
Matters needing attention
1. wrench tool:
(1) When using, choose a wrench with appropriate specifications according to the shapes, specifications and working conditions of screws and nuts.
(2) During operation, the pulling force should be applied to the thicker side of the opening to prevent the opening from being splayed and damaging the nut and wrench.
(3) Except for the socket wrench, no other wrench can be used with the booster lever to prevent the wrench or threaded connection from being damaged.
2. Screw screwdriver:
(1) Select the appropriate screwdriver according to the groove width and groove shape of the screwed or loosened screw head;
(2) Don't use a screwdriver to tighten or loosen the screws on the workpiece held in your hand, but clamp the workpiece in the fixture to prevent injury;
(3) Don't pry anything with a screwdriver or remove metal burrs and other objects.
3. Hammer and pliers:
(1) When using a hand hammer, carefully check whether the connection between the hammer head and the hammer handle is firm, and hold the back end of the hammer handle when holding the hammer. There are three ways to swing a hammer: wrist swing, elbow swing and arm swing.
A, the wrist swing is hammered only by the wrist action, with small hammering force, but accurate, fast and labor-saving;
B, the swing arm is that the wrist, elbow and the whole arm swing together, and the hammering force is the largest;
C, elbow swing is the wrist and elbow swing together for hammering, and the hammering force is between wrist swing and arm swing.
(2) The use of pliers should be limited to its designed purpose: clamping or cutting, and never loosen the nut with pliers.
interrupt
Jack is a kind of light and small lifting equipment, which uses rigid lifting parts as working devices and lifts heavy objects through top brackets or bottom brackets. There are two types: mechanical and hydraulic. Hydraulic jack is widely used because of its compact structure, stable work and self-locking function. Its disadvantages are limited lifting height and slow lifting speed.
Usage: Take the hydraulic jack as an example:
(1) Before jacking the car, wipe the top surface of the jack clean, tighten the hydraulic switch, and place the jack at the lower part of the jacked part so that the jack is perpendicular to the jacked part to prevent the jack from slipping out and causing an accident.
(2) Rotate the jacking screw to change the original distance between the top surface of the jack and the jacked part, so that the jacking height can reach the jacking height required by the automobile.
(3) Block the front and rear wheels of the car with triangular wedges to prevent the car from slipping when jacking.
(4) Press the jack handle up and down with your hands, and the jacked car will gradually rise to a certain height. Put the car stool under the frame, and it is forbidden to pad the car with fragile items such as bricks. When getting off the bus, check whether there are obstacles under the bus to ensure the safety of the operators.
(5) Slowly release the hydraulic switch, so that the car can descend slowly and steadily and stand firmly on the parking stool.
Matters needing attention
(1) It is forbidden to work under the car when jacking or descending.
(2) Loosen the hydraulic switch slowly, and let the car descend slowly. The car cannot descend too fast, otherwise it will be prone to accidents.
(3) When jacking the car on the soft road with a jack, materials (such as boards, etc.) should be used. ) A large area and able to withstand pressure should be placed under the jack base to prevent the jack from sinking due to the heavy weight of the car. The contact position between the jack and the car is correct and firm.
(4) When the car is jacked up by the jack and the hydraulic switch is in a tight state, if there is an automatic drop fault, the reason should be found out immediately, and the fault can be eliminated in time before continuing to use.
(5) When the jack is found to be short of oil, the specified oil should be replenished in time, and it cannot be replaced by other oil or water.
(6) The jack should not be heated by fire, so as not to damage the cup and apron.
(7) The jack must be placed vertically to avoid oil leakage and failure.
Car lift
Car lifts are used to lift cars during car maintenance. When the car travels to the lifting station, it can be lifted to a certain height by manual operation, which is convenient for car maintenance. According to the function and shape, elevators can be generally divided into three categories: two-column, four-column and scissors.
Precautions for use
(1) The total mass of the vehicle cannot be greater than the lifting capacity of the elevator.
(2) Make the car's center of gravity close to the elevator's center of gravity as far as possible according to the different vehicle types and parking positions; Be careful not to be biased. In order to open the door, there should be a certain distance between the carriage and the column.
(3) Rotate, extend and adjust the boom to the designated position of the automobile chassis, and ensure firm contact.
(4) Before lifting the car, the operator should check whether there are obstacles and personnel activities around the car to prevent accidents.
(5) When lifting the car, it should be lifted repeatedly at a lower position from the ground, and it can only be lifted to the required height when there is no abnormal phenomenon.
(6) After the car is lifted, it should land on the ratchet wheel and lock it immediately.
Lifting crane
There are four kinds of cranes in common use: portal crane, cantilever crane, monorail crane and beam crane. Cantilever cranes are widely used in automobile disassembly training, which can be divided into two categories: mechanical and hydraulic.
(1) Mechanical cantilever crane: Turn the winch and ratchet wheel through the handle, contract or extend the chain, so that the heavy objects can rise or fall and move for a short distance.
(2) Hydraulic cantilever crane: During the lifting process, due to the action of the oil pump, pressure oil enters the working cylinder, pushing the ejector rod to move outward, thus lifting heavy objects. When the oil valve is opened, the oil in the working cylinder will flow back to the oil tank, so that the pressure will be reduced and the weight will be put down.
Matters needing attention in the use of lifting equipment:
(1) Lifting heavy objects is not allowed to exceed the rated load.
(2) The steel wire rope and rope buckle shall be installed firmly.
(3) The hanger should be as close to the ground as possible to reduce shaking. When lowering the hanger, be steady and don't rush it.
(4) It is forbidden to use a crane to drag lifting parts that are not within the lifting range.
special tool
Piston ring removal pliers
Piston ring dismounting pliers are special tools for dismounting piston rings, so as to avoid the piston rings from being broken due to uneven stress. Precautions for use:
1. When using the piston ring pliers, clamp the ring on the piston ring pliers to the opening of the piston ring, gently and evenly hold the handle, so that the handle will slowly shrink. At this time, the ring clamp will slowly open the piston ring, so that the piston ring can be taken out or put into the piston ring groove.
2. When the piston ring is removed by using the piston ring removal pliers, the force must be uniform to avoid the piston ring from breaking due to excessive force, and at the same time, the hand injury accident is avoided.
Valve spring dismounting frame
The valve spring dismounting rack is a special tool for dismounting the overhead valve spring. When in use, the mounting bracket is pressed on the valve, the pressure ring is aligned with the valve spring retainer ring, and then the handle is pressed, so that the valve spring is compressed. At this time, you can remove the lock pin or lock piece of the valve spring, and slowly loosen the handle to take out the valve spring retainer ring, the valve spring and the valve.
bencher
Puller is a special tool to remove the gear or bearing installed on the shaft with interference fit. The commonly used puller is manual, and a pressure screw and a claw are installed on the rod-shaped bow fork. When in use, a gasket is placed between the shaft end and the compression screw, the gear or bearing is pulled by the claw of the puller, and then the compression screw is tightened, so that the gear and other interference-fit installation parts can be pulled down from the shaft.
grease gun
Grease gun, also called grease gun, is a special tool for filling grease (butter). The usage method is as follows:
(1) Fill with butter
① Pull out the pull rod to make the plunger move backwards and loosen the front cover of the barrel of the grease gun.
② Divide the clean butter into small balls, and slowly put them into the cylinder barrel, so that the butter balls can stick to each other as much as possible, so as to facilitate the discharge of air from the cylinder barrel.
③ Replace the front cover, push back the pull rod, and the plunger moves forward under the action of the spring, so that the butter is in a compressed state.
(2) Oil injection method
(1) aim the grease gun connector at the lubricated grease gun nozzle (grease gun), straight in and straight out, without deviation, so as not to affect the filling of butter and reduce the waste of grease.
(2) When injecting oil, if the oil is injected, stop immediately, find out the cause of the blockage, and then inject oil after it is eliminated.
(3) The main reason for not feeding oil when filling grease.
① There is no butter in the barrel of the grease gun or there is air between the butter in the pressure barrel.
② The oil pressure valve of the grease gun is blocked or the oil injection joint is blocked.
③ The grease gun spring is too soft due to fatigue, insufficient elasticity or spring fracture failure.