General Information   |  Technical Description

A metallic cold laminated bench of profiles, 2mm plate metallic seals, dimensions adapted to the benches weight and volume of the mechanical and electromechanical elements. On previous general bench, which rests on the ground on neoprene shock absorbers, reducing therefore the vibrating transmissions on adjacent zones, different sliding and adjustable metallic subbancadas are builded in three space axes, allowing to lodge different mechanical elements.

In an end of the general bench, the drag group settles. Formed by an electrical or electromechanical machine of agreed characteristics to the type of tested gear boxes. From fast tourism (up to 7000 rpm.) under torque, to slow diesel engines (2000 rpm.) elevated torque. The drag machine will be electronically controlled by means of tiristors regulators in 2 or 4 quadrants; this is, working as engine or engine and brake. This technology makes it possible to precisely simulate the static and dynamic conditions of the thermal engines, being able “to send” the transmission with similar accelerations to the vehicles real ones and “slow” the systems inertia with similar braking capacity. After the drag system, settles the build-up kit and anchorage of the gear box. It is composed by a flexible connection in the engines axis or motoreducer, that connects with an axis settled in each of its ends on autooscilant bearings. The bearing supports and the “bell” of anchorage of the box to try, are fixed to the general bench. In the end of the power shaft are the interchangeable tools, to drag different hydraulic converters and/or transmission primary axes. This tools are, with the fixing boxes tools, interchangeable, to give the bench an universal use. Fixing the box to the corresponding bridle, and connected with its tools, the bench can adopt different configurations according to the type test: Test in emptiness, Inertial test, Stationary test and combined Inertial-Stationary test. The length of bench can be limited when the bench tests in emptiness is applied. For the test in emptiness, the bench does not need any other mechanical element. This is a machine of lower cost, that allow elemental functional tests, but enough to evaluate repairs and/or failures of less importance.

The inertial test consist on connecting a turning mechanical system in the output axis of the box to test. The inertial benches have an inertia turning disc set, builded on a general adjustable bench and right after the gear box. According to the application, the inertial system varie from a simple calculated disc used to simulate a vehicles fixed inertia, to a manual preselected 6-7 disc system or automatically, with which is possible to obtain great number of inertial stages, to simulate the masses and conditions of vehicle loads. The inertial system has a pasant axis with bridles in its ends. The front bridle allow the connection of the gear boxes output system to the output axis, by means of an articulated tree or homocinetic transmission. For “transversal” gear boxes, with the built-in differential and double exit, two inertial systems transversally located can be used or by blocking one of the exits using just one. Analogously it can be processed in 4x4 traction vehicle boxes. The x-y axe and set height regulation, can be manual or motorized. The use of inertial systems allows to simulate the vehicles load conditions in a transitory phase, both in acceleration as in deceleration. This way, combining it with the drag capacity and benches slowing down, it is possible to make load tests accelerating “against” the inertial system and “pushing” or dragging from itself, at the same time as it slows down in the engine.

The gears, brakes, clutches, hydraulic converter and other movable organs, are used for transitory loads, allowing us detect failures or wrong functions that would not be demonstrated in a test in emptiness, such as slidings, expulsion of marches, heatings, noises and vibrations, etc.

The stationary test forces to offer a resistance to the gear boxes exit turn that simulates its habitual state of operation. One or several dynamometric brakes that apply a controlled pair electronically are incorporated, according to the programmed test cycles. This device allows “to maintain” the load on the box each time it is considered, simulating, for example, going up a port, elevated load long travels , etc.

A dynamometric brake is a machine that offers a resistance for any engines turn, electronically controlled with different performance ways (n=cte, M=cte, M/n, n2, etc.) According to the characteristics of the boxes to try, different types of dynamometric brakes will be applied.

If the gear box or transmission is transversally assembled, it is necessary to duplicate the inertial and braking systems, unless the differential blocks and the brake is applied to one of its exits. In order to contemplate the total types of gear boxes, some benches are constructed with the drag and braking system, with movement ability in the three space axes.

It is possible to combine inertial and stationary ways connecting the dynanometer in the free axis of the inertial system. This mode is the one that simulates in a more realistic way the vehicles working conditions in highway.

All the important involved test parameters, are evaluated by electronic precision sensors. The measurement channels are multiple of 16, although in most cases 16 channels are enough. The sensors centralize in a nearby closet next to the following mechanical systems, where the corresponding hydraulic and electrical connections are canalized.

The basic bench incorporates the following transducers:

• Measurer of entrance regime (to encoder, tacodinamo, analogical exit of variation of speed or magnetic receiver).
• Measurer (s) of exit regime (idem)
• Measurer of torque drag. (Intensity of variation of speed, cell of load or torsimeter).
• Measurer (s) of braking torque(s) (idem)
• Temperature (s), (thermocouple type soundings or Pt-100)
• Oil volume (turbine with regime receiver)
• Pressures (main, of lubrication, converter, clutch of bridge, modulation, retarder, NBS, KV1, KV2, etc.) 

In addition, it is possible to include other parameters or channels to read things like noise, vibrations, etc., as other type sensors whose mission is to detect any benches anomaly and produce a security emergency shutdown of the bench elements and/or for the workers security.

All the electrical aparellaje of protection and maneuver, settles inside a metallic closet, that includes the following elements:

Electronic speed variator of 2 or 4 quadrants (engine or engine/ brake) that is in charged of making turn the engine at a proportional speed to the introduced slogan. These variators are fed by a three-phase tension, admitting different ranks, according to the necessities. They can feed engines of constant and alterne current and it regulates the speed of those engines, or by internal references (armor), or by external references (encoder, tacodinamo).

Power rate reader for the variator feeding(three-phase) activated by a control signal. This reading mechanism usually is complementary to the one that has to be in the general installation of the factory where the bench is going to be used.

Rate measuring power mechanisms for the rating and beginning of the variator (INABLE and START) with a certain sequence, as well as others for the investment in the direction of the engines rotation.

Rate engines vehicle activation (normally three-phase) and fundamental for the good operation of this engine.

Connection bornals of the different signals: control of rating mechanisms, wiring of encoder or tacodinamo, heat screens or emergency mushrooms, controls and box lights.

This box can go anchored to the wall or consist of one to three modules of 2x1 M., according the controlled power. The installation has to go by all means provided with Neutral and Earth, that will be connected to all the benches participant elements (benches, different boxes, engine…).

A standardized electronic 19 " box, centralizes different racks and systems of measurement and control, including the informatics equipment, with the following elements

Rack of 2 u. of height, with synoptic title “Gear box test benches” and general switch key for the activation/decontamination of this box.

Converting units in 3 u. height rack, with 8 converting cards by unit, to transform the signal of exit of each used sensor into the bench in a proportional tension that is introduced in the system of data acquisition. There are existing cards that turn frequency (typical signal of a magnetic receiver of rpm), intensity (pressure sensors), millivolts (temperature sounds K or Pt-100 type) to a proportional tension 0 to 10 volts adapted for the acquisition data card.

Control unit, from where the test bench is handled. From this rack, of 3 u. of height, they activate, via software or manually, the DS of control for the rating and beginning of the variator, the speed of turn of the engine by means of a potentiometer with dial become or via software is varied and must access to a pulser to force an emergency shutdown in case of any anomaly. In addition, from this rack, it is possible to manual or automatically start, different electrovalves from the gear boxes like, for example, retarder and the brake.

Regulation unit. Is the one in charge of regulating the load introduced by the brake (in case of stationary tests).It is comped by a P.I.D. card, for torque and power card control to attack the brake with the necessary current, according to the type of brake (s) employed. By means of a potentiometer of a multiturn dial (manual control) or by means of an analogical exit of 0 to 10 volts of the data acquisition card (automatic control) the introduced load in the brake can be regulated from 0 to 100%. It exists, in this unit, the possibility of controlling the brake in 4 regulation ways, Constant Torque (m), Constant Speed (n), Constant M/n and Angle (Ð) Constant.

Complete computer science system made up of the following elements: On a fixed tray a 17 " color monitor is placed.

On another fixed tray the CPU is fixed, normally Pentium III of last technology, CD-ROM, operating Windows 98 system with the data acquisition card (s) (16 analogical entrance channels, 2 analogical exits 0 to 10 volts, 16 digital entrances and 16 digital exits) in ISA or PCI format, with a speed of sampling of up to 40 KHz.

In a telescope tray, movable, they locate the keyboard in special format for boxes and a trackball for more comfortable use upon the tray.

In another movable tray, the color injection ink printer where all the numerical and graphical results will be printed.

Entrance platform and cable exit where the different cable connectors and network connection are mechanized.

Inside the box, the different types pass-cable canals, DIN track fixation of differential and thermal box protection as other elements, strip of different plugs to be able to connect racks and the informatic system.

The final system of the test bench is totally modular as the 3 existing closets are connected to each other by means of hoses of 6 meter length (or superior, according to specifications), with ununplug militar connectors that make each box totally independent, without limitation as far as their final positioning.

As far as software, different types exist according to the type from gear box and the test that is going to be made. All of them are based on the same philosophy, to acquire, to control, to visualize and represent in real time all the sensor parameters that take part in the test bench and archive them for postprocesses. They are made up of the following blocks

Calibration file, where they are formed for each entrance analogical signals, the channel entrance number, name, minimum and maximum stress range and the corresponding minimum and maximum physical magnitude margin for those tensions.

Configurating box file, where the trying box type is defined, its validation ranks to see the box as correct, its ranks of alarm to abort the test, control curves of engine and brake and all necessary characteristics.

Test accomplishment, manual form (varying engines speed by the worker, the introduced load by the brake and visualizing the parameter values without limit time) or by the automatic way (driving the engine and brake by means of a control curve and with the computer checking that the acquired values are within the margins of the good box operation during the programmed test times).

Test results, visualizing numerically and graphically any type parameters that take part in the test, being able to represent them based on the time or in function of others, to visualize 1, 2 or 4 simultaneous graphs.

Impression of the results, in a numerical way, with a stuffed test protocol with the acquired parameters validating or not the box, with a numerical result of the captured values and validated in table or graphical format, printing up to 4 graphs of different parameters with numerical annexes.

Test comparison, once the test is made, the box tested can be chosen like pattern of all same type boxes to be able to compare them. We can define the curved pattern with a certain tolerance (D x, D y) so that all the curves of the successive tests enter within those margins being able to give them as valid.