Electric wrench refers to an electric tool for tightening and loosening bolts and nuts. It is a tool for tightening high-strength bolts. It is used for initial tightening, final tightening and initial tightening of torsional shear high-strength bolts in the construction of large hexagon head high-strength bolts for the installation of steel structure bridges, plant buildings, chemical industry and power generation equipment, as well as occasions with strict requirements on the torque or axial force of bolt fasteners.

定轉矩電動扳手是一種能自動控制轉矩的電動扳手。它適用于需要用高強度螺栓連接的橋梁結構、大型鋼塔、鋼結構廠房、冶金設備的構架、大型起重機架、礦井鋼架等工程中及大型柴油機、發電設備、化工設備中，要求恒定的夾緊力連接的螺栓也可用定轉矩扳手來緊固。

Constant torque electric wrench is an electric wrench that can automatically control torque. It is applicable to bridge structures, large steel towers, steel structure plants, frames of metallurgical equipment, large crane frames, mine steel frames and other projects that need to be connected with high-strength bolts, as well as large diesel engines, power generation equipment and chemical equipment. Bolts requiring constant clamping force can also be tightened with constant torque wrenches.

特別在現代橋梁建設中，定轉矩電動扳手是實現以“栓焊梁”代替“鉚焊梁”的有效工具。這對簡化工地安裝工序、降低建橋成本、減輕勞動強度，從而加速橋梁建設具有較大的意義。

Especially in modern bridge construction, the constant torque electric wrench is an effective tool to realize the replacement of "rivet welded beam" with "bolt welded beam". This is of great significance to simplify the site installation process, reduce the bridge construction cost, reduce the labor intensity, and accelerate the bridge construction.

定轉矩電動扳手的轉矩以電氣裝置來進行控制。這種電動扳手具有耗電量少、噪聲小、調節靈活、能自動停機、轉矩穩定等優點。

The torque of constant torque electric wrench is controlled by electrical device. The electric wrench has the advantages of low power consumption, low noise, flexible adjustment, automatic shutdown, stable torque and so on.

電動扳手是裝卸螺紋聯接件的手持式電動工具，廣泛應用于汽車、拖拉機、電機電器、動力機械、閥門、水泵、紡織機械等制造業的裝配工作中，在化工、水泥預制件、塑料成型等作業中則用于生產流程中裝拆真空罐、反應釜和水泥模板、帶螺紋塑料件的脫模工作；也可用在鐵道、橋梁、建筑等工程中作水泥軌枕、桁架節點、角鋼腳手架等結構的安裝、檢修和拆換工作。

Electric wrench is a hand-held electric tool for loading and unloading threaded connectors. It is widely used in the assembly of automobiles, tractors, motors and electrical appliances, power machinery, valves, water pumps, textile machinery and other manufacturing industries. In chemical industry, cement prefabricated parts, plastic molding and other operations, it is used for the assembly and disassembly of vacuum tanks, reactors and cement templates in the production process Demoulding of threaded plastic parts; It can also be used for the installation, maintenance and replacement of cement sleepers, truss joints, angle steel scaffolds and other structures in railways, bridges, buildings and other projects.

當螺母的端面與工件端面接觸后，阻力矩急劇上升，轉動的螺旋槽使滾珠帶著主動沖擊塊克服摩擦力和工作彈簧的壓力向后移動，使主動沖擊塊與從動沖擊塊互相嚙合的牙脫離嚙合。此時，從動沖擊塊不移動，而主動沖擊塊繼續向后移動。在轉過從動沖擊塊的牙后，由于工作彈簧的作用使主動沖擊塊瞬時前移，并沿螺旋槽產生一個角加速度，主動沖擊塊撞擊從動沖擊塊，兩牙產生碰撞。然后螺旋槽又使滾珠和主動沖擊塊后移，脫離嚙合。這樣周而復始產生一次又一次的碰撞，獲得所需的沖擊力矩，使螺母緊固。

When the end face of the nut is in contact with the end face of the workpiece, the resistance moment rises sharply, and the rotating spiral groove makes the ball move backward with the active impact block to overcome the friction and the pressure of the working spring, so that the teeth meshed between the active impact block and the driven impact block are disengaged. At this time, the driven impact block does not move, but the active impact block continues to move backward. After turning the teeth of the driven impact block, the active impact block moves forward instantaneously due to the action of the working spring, and an angular acceleration is generated along the spiral groove. The active impact block impacts the driven impact block, and the two teeth collide. Then the spiral groove moves the ball and the active impact block backward and out of engagement. In this way, collisions occur again and again to obtain the required impact torque and tighten the nut.

如將電源開關接到反轉位置即可擰出螺母。雙重絕緣單相串勵電動扳手在操作手柄上裝有兩只開關。一只為工作開關，是操縱起動和停止的；另一只是專門為改變電樞正反轉而設置的，兩只開關不可接反。

If the power switch is connected to the reverse position, screw out the nut. The double insulated single-phase series excitation electric wrench is equipped with two switches on the operating handle. One is a working switch, which operates start and stop; The other one is specially set to change the forward and reverse rotation of the armature, and the two switches cannot be connected reversely.