AGRICULTURAL MACHINES FUNCTIONAL AND SAFETY TESTING SERVICE TEST REPORT

Transcription

1 AGRICULTURAL MACHINES FUNCTIONAL AND SAFETY TESTING SERVICE TEST REPORT No CUT-OUT CLUTCH: EK 62/2S MANUFACTURER: GKN Walterscheid GmbH HAUPTSTRASSE LOHMAR (GERMANY) Rome, November 2003

2 TESTING CARRIED OUT IN COMPLIANCE WITH ENAMA SPECIFICATIONS NO. 49 REV. 01, BY: ING. MICHELE GALDI (ENAMA TECHNICAL COMMITTEE) Geom. Renato Delmastro (CNR Turin) Table of contents Description 3 How the device works 4 Purpose of tests 5 Description of test bench 5 Application 7 Dynamic testing 8 Results of tests 11 Resetting of cut-out clutch 11 Residual torque 11 Cut-out time 11 Notes on functionality 11 To facilitate interpretation of the results, it should be remembered that: 1 rpm = 1 min -1 1 MPa = 10 bar 1 kw = 1.36 CV 1 m 3 /s = 3600 m 3 /h 1 m/s = 3.6 km/h Moment of force = product of a force and its distance from the axis of rotation (arm). Unit of measurement = Nm PTO = Power Take-Off. 2

3 Description The cut-out clutch (Model EK 62/2S), manufactured by the company GKN Walterscheid GmbH based in Lohmar (D) has been designed to quickly interrupt the power transmission towards agricultural implements. In greater detail, the system has the job of disengaging implements powered by the pto cardan shaft, making it possible to stop implement operation for practical reasons and in the event of an emergency. The cut-out clutch is a solution that will make mixer feeder wagon and round balers safer, but it can also be used for other machine categories. A Fig.1 Schematic views of device showing one of the four splines of the disengaging ring (A). 3

4 How the device works The cut-out clutch (Model EK 62/2S) works through the simple activation of a metal cog which, by contrasting one of the four radial splines of the rotating gear s ring (A), makes it possible to disengage the cardan shaft drive and stop the implement connected to it. The cut-out clutch has the following characteristics: a ball-type disengaging system loaded by belleville springs; an external disengaging ring consisting of 4 stop sections designed to ensure, together with the locking system, that the transmission comes to a halt; a housing for the device s mechanism; belleville springs for the engaging of balls under likely working conditions; possibility of flanging on several types of implements in order to offer a broader range of use. 4

5 Fig. 2 The device during bench tests. Purpose of tests Tests set out to ascertain the actual ability of the system to disengage the drive in order to permit its use for agricultural implements powered by cardan shaft drive. In greater detail, the tests sought to verify the device s ability to disengage the drive upon the intervention of the safety sensor and to re-engage the drive only upon a conscious action on the part of the operator. Also tested was the force required to disengage the mechanism when under different torque conditions. Disengaging is achieved via a metallic latch, opposing the rotating rings, the required force is provided by the device s contrasting structure, so the force required to operate the metallic latch remains unchanged. Description of test bench The test was performed on a bench built to test the loaded disengaging 5

6 system (figures 2 and 3). The bench consisted of: a power generator (electrical motor); sensors used to acquire the speed of rotation and torque absorbed by rotation; a brake; a cardan shaft connecting the generator to the device being tested; a safety limiter; a release system for the device control unit. Technical data: ELECTRIC UNIT Power (kw) 200 Power take-off speed (rpm) 540 BRAKE Type: disc with caliper brake Braking couple see limiter SAFETY LIMITER GKN Walterscheid GmbH (Nm) 500 TORQUE METER Type GKN Walterscheid GmbH End scale (Nm) 2500 Sensitivity (%) +/- 1 Passband (Hz) 500 CUT-OFF ACTUATOR Type: GKN Walterscheid GmbH CUT-OUT CLUTCH Type: GKN Walterscheid GmbH mod. EK 62/2S AIR TEMPERATURE (C ) 18 6

7 a d c b e Figure 3 - Diagram of test bench: a) motor 200 kw; b) device being tested; c) torque meter; d) safety limiter; e) brake. Application In choosing procedures for the test cycle, the operations performed by field users have been respected, pursuant to the test protocol. The following sequence was adopted: 1. positioning of cut-out clutch in engaged position; 2. start-up of power electric unit; 3. stabilisation of speed of rotation of power take-off; 4. start of acquisition of drive s functional parameters (torque transmitted, number of revs, cut-off time and residual torque) using torque meter; 5. cutting off of the clutch by using the electrically-operated mechanical latch system; 6. return to point 3 and repeat test cycle to check values and the device s effectiveness several times; 7. stop of data acquisition. 7

8 Dynamic testing The following tests were carried out using the above sequence: 1. Tests without braking torque (close to 0 Nm) with speed of rotation of the power unit of 540 rpm to simulate PTO (power take-off) speed of tractors (fig. 4); 2. Tests with braking torque, measured upon disengaging of the cutout clutch, of 220 Nm, and PTO speed of 540 rpm (fig. 5); 3. Tests with braking torque, measured upon disengaging of the cutout clutch, of about 350 Nm and PTO speed of 540 rpm (fig.6). Figure 4 Graph showing one of the tests performed (cut-off without torque transmitted). 8

9 Speed of rotation (min -1 ) Torque (Nm) Cut-off time (sec) Residual torque (Nm) Without braking torque Table 1 Average values measured for three tests (cut-off without torque transmitted). Figure 5 Graph showing one of the tests performed (cut-off with torque of 224 Nm transmitted). 9

10 With average braking torque of 224 Nm Speed of rotation (min -1 ) Torque (Nm) Cut-off time (sec) Residual torque (Nm) Table 2 Average values measured for three tests (cut-off with torque of 224 Nm transmitted). 10 Figure 6 Graph showing one of the tests performed (cut-off with torque of 355 Nm transmitted). Speed of rotation (min -1 ) Torque (Nm) Cut-off time (sec) Residual torque (Nm) With average braking torque of 355 Nm Table 3 Average values measured for three tests (cut-off with torque of 335 Nm transmitted).

11 Results of tests Notes on functionality Resetting of cut-out clutch As the graphs show, after the device has been used, the implement can only be restarted once the PTO has reached a speed of rpm and below. This value is always less than the speed of rotation of the tractors PTO when these are operated with the engine at idle RPM ( rpm). To re-engage the clutch, it is thus necessary to stop the tractor s PTO or engine; it is this characteristic that ensures the operator s safety. Residual torque Residual torque was zero under all test conditions, as can be seen from the 3 graphs. Cut-off time The cut-off time was less than 1 sec. under all test conditions. The following considerations can be made in view of the tests performed and data given in the present test report: The cut-out clutch (Mod. EK 62/2S), designed by GKN Walterscheid GmbH, is capable of disengaging the mechanical driving power to the working sections of a number of agricultural implements, thus achieving the set goal of improving operator s safety; During laboratory tests no anomalies or malfunctions were encountered under any of the operating conditions to which the device was subjected. All disengaging and engaging operations were precise and immediate; Finally, the use of agricultural implements can be safer by equipping them with a safety device such as the EK 62/2S, which allows the operator to stop the implement whenever necessary. 11

12 THE PRESENT TEST REPORT, REGARDING THE CUT-OUT CLUTCH MOD. EK 62/2S, IS VALID FOR A PERIOD OF FIVE YEARS OR UNTIL REFERENCE REGULATIONS ARE ALTERED, AND IS OFFICIALLY RECOGNISED BY ENAMA MEMBERS: ASSOCAP (Associazione Nazionale dei Consorzi Agrari) (National Association of Farm Consortia) CIA (Confederazione Italiana Agricoltori) (Italian Farmers Confederation) COLDIRETTI (Confederazione Nazionale Coltivatori Diretti) (National Confederation of Independent Farmers) CONFAGRICOLTURA (Confederazione Generale Agricoltura) (General Farming Confederation) UNACMA (Unione Nazionale Commercianti Macchine Agricole) (National Union of Farm Machine Dealers) UNACOMA (Unione Nazionale Costruttori Macchine Agricole) (National Union of Farm Machine Manufacturers) UNIMA (National Union of Farm Mechanisation Enterprises) (National Union of Farm Mechanisation Enterprises) AND BY MEMBERS OF THE EXECUTIVE COUNCIL OF THE ENAMA, IN WHICH THE FOLLOWING ARE ALSO REPRESENTED: MIPAF (Ministry for Agricultural and Forestry Policies) Regions and Autonomous Provinces ISMA (Istituto Sperimentale per la Meccanizzazione Agricola) (Experimental Institute for Agricultural Mechanisation) ENAMA - ENTE NAZIONALE PER LA MECCANIZZAZIONE AGRICOLA (National Agricultural Mechanisation Body) VIA LAZZARO SPALLANZANI, 22/A ROME TEL. 06/ FAX 06/ info@enama.it