This service manual describes the composition of the Model GR-700EXL-1 and GR-700EX-1 rough terrain crane, its repair, check and adjustment methods and other relevant matters. Note that this service manual does not provide the information in the separate service manuals given below. This service manual applies to the cranes with the specification numbers given below. Check the specification number on the nameplate of your crane. tadano cranes dealers,tadano crane dealer,tadano cranes.
Tadano GR-700EXL-1 Service Manual
Read the separate operation and maintenance manual and the parts catalog for repair and maintenance of the crane in conjunction with this manual. If the parts needs to be replaced, check the disassemble units and sales units in the parts catalog before replacing them.
Most accidents that occur during machine operation and maintenance are caused by failure to observe basic safety rules and precautions. Before operating your machine or performing maintenance, read and become familiar with all the safety precautions and recommendations given in this section. Remember that failure to observe even a single precaution could involve you and the people around the machine in a serious accident.
Foreseeing potential dangers is vital for preventing accidents. All personnel working with the machine, including the supervisor, machine operator and oiler, should be sensitive to potentially dangerous situations and take the necessary measures to prevent accidents.
Safety precautions and recommendations are outlined in this section and are also included in the operation and maintenance instructions given in subsequent sections. Warning labels are also provided on the machine.
Servicemen inexperienced in the units of this machine should be cautious about safety operations. They must acquire sufficient knowledge about the equipment before dismounting and disassembling it. Before dismounting each component, a serviceman should read this service manual thoroughly and find out the weight of the component, then lift it by proper means.
Tadano GR-700EX-1 Service Manual
Hydraulic oil (P) from the pump flows to areas A and B shown in Figs. 1 and 2 via the path in the regulator casing. The oil also flows to small-diameter end H of the servo piston. The oil flowing to area A applies leftward pressure to the compensation piston.
When the pump pressure is below a certain level, the spool does not move because the leftward force of the compensation piston on the spool is less than the pressure of the compensation spring. In this situation, the seating area C closes and the seating area E opens. Therefore the oil at the servo piston’s large-diameter end G flows out from the port D to the drain line via the spool. Then the servo piston’s large-diameter end G is pushed by the pressure exerted on the small-diameter end H, to stay in the maximum discharge rate position.
When the pump pressure exceeds the 1st turning point (P1 in Fig. 3), the leftward force of the compensation piston on the spool overcomes the pressure of the compensation spring and the spool is moved to the left. As a result, seating area E closes, and seating area C opens. The hydraulic oil in area B flows to the servo piston’s large-diameter end G via the port D pushing the servo piston to the right decreasing the discharge flow rate. The rightward movement of the servo piston is transferred to the feedback lever via the fulcrum J . The feedback lever revolves around the pin on the top of the fulcrum plug. A pin (A) is inserted in both the end of the feedback lever and the hole of the sleeve. When the feedback lever revolves, the sleeve moves to the left, and seating areas C and E open where the Hydraulic powers of the small and large-diameter ends of the servo piston are balanced. When the pump pressure decreases, the compensation spring pushes back the spool, causing seating area C to close and seating area E to open. The hydraulic oil at the servo piston’s large-diameter end G is discharged into the drain line, causing the servo piston to move the left, increasing the discharge rate. The movement of the servo piston is transferred to the sleeve via the feedback lever, and seating areas C and E open or close so that the servo piston, under the pressures on both ends, follows the movement of the spool.
As explained above, the discharge rate of the pump is controlled by the balance of pressure on the spool, the pressure setting compensation spring, and the balance of pressure on the large and small-diameter ends of the servo piston. The maximum and minimum discharge rates are set by adjustment screws 954 and 953, respectively. The 1st turning point is set by the adjustment screws. Gradients of the pressure discharge lines are determined by the spring constant.