An interesting project supplied several years ago, was the design and supply of a complete test bed for Aircraft Starter Motors for a customer specialising in the inspection, reconditioning and rebuilding of aircraft components.
The particular problem in this case was the variety of test equipment required to test all of the variations of starter motors which the company service.
The customer was looking for a single test bench, which would be very flexible, easy to use and could be pre-programmed with as many tests as possible. The specification was such that the input shaft must be able to rotate up to 24,000 rpm and the max. stall torque was to be in the order of 75Nm.
Pimbo Industrial Design Ltd was the main contractor for this project. Compact Orbital Gears Ltd. Rhayader supplied the motor-gearbox combination.
The Starter Motor was mounted on a torque measuring platform manufactured by Arrow Engineering. The rig was designed to run in one of four modes which are as follows:-
Speed; Torque; Staff Torque; Flywheel
During the flywheel test, the dynamometer becomes an ‘electronic’ flywheel. A colour touch screen has recently been added to this rig, which as well as allowing the operator to set up each test, also gives an on-line display of speed, torque and other test parameters.
Control and Loading System for a Helicopter Auxiliaries Gearbox Test Rig
Another project completed more recently, was the design and supply for the control system of a Gearbox Test Rig for G.K.N. Westland Aerospace Transmissions.
The gearbox under test was the auxiliaries gearbox for the EH101 Merlin Helicopter. This Gearbox drives an alternator and two Hydraulic pumps. During the test, this box is driven by a Eurotherm Drive D.C. Drive and Motor, through a speed up gearbox being supplied by Compact Orbital Gears Ltd. Of Rhayader. The control system can be programmed to perform a number of tests, different speeds; loads; time, etc. As each test is performed, set point and actual data is logged in a SCADA System, running on a locally mounted P.C.
One innovative feature of this test rig, is the use of an electronic power converter to load the Alternator. This provides very accurate control of the alternator load and as it is coupled to the mains supply through a transformer, it provides recovery of most of the generated energy, instead of being wasted in load banks.
Rebuild of an AC and DC Motor Test Area
When the A.C. and D.C. Motor Manufacturer Mawdsleys Ltd. moved their factory from Dursley to Gloucester, they took the opportunity to automate the Test Area. Pimbo I. D. Ltd provided the complete new control system. This allowed the test operators the freedom to select the correct supply ( Mains, Drive or Generator ) and appropriate load for any specific test. The system was controlled by a multiple PLC System, and included 5 Touch Screen displays.
Control and Loading System for an Aircraft Propeller Combining Gearbox Test Rig
This project was again for the supply of a control system for a Gearbox Test Rig again for G.K.N. Westland Aerospace Transmissions. In this case the Gearbox under test was a combining gearbox with two high speed input shafts driving on its output a 6 bladed propeller.
The test rig was of the mechanical recirculating type with the losses being made up by a D.C. Motor and Drive.
As with the EH101 gearbox test rig the Drive and motor were supplied by Eurotherm Drives with the speed up and loading Boxes being supplied by Compact Orbital Gears Ltd. of Rhayader. Pimbo I D Ltd were responsible for the complete control system, including the Torque loading, wind up control hydraulics. With this rig it was possible to simulate flight loads to the Gearbox output shaft via hydraulic actuators, and again Pimbo Industrial Design was responsible for the control system to achieve this.
Supply of 4 Aircraft Generator Rigs
We have recently installed 4 Generator Test Rigs on to the Turner Aviation Site in Glasgow. Two of the generator rigs where for testing 20 Kw DC units, plus one dedicated for up to 30,000 rpm, 150 Kw AC and the fourth being a multipurpose rig for testing both AC and DC Units, again up to maximum loading of 125 Kw, but up to a maximum speed of 20,000 rpm.
As at Westland both AC Rig loading was achieved using an energy recovery system, which provides recovery of most of the generated energy back into the mains supply, instead of being wasted as heat in load banks.
Supply of an Aircraft HP / LP Fuel Pump Test Rig
The requirement here was for a test rig to test two types of two stage fuel pumps. Each pump had a low pressure centrifugal pump stage followed by an accurate high pressure gear pump.
Turner Aviation in Glasgow had a contract to service and rebuild these pumps. This had to be followed by a run in and performance test to certify the pump for use.
Pimbo Industrial Design was the main contractor and supplied the Drive and Control System Equipment. Whilst the Fuel Fluid Skid was built by Denco of Hereford and Compact Orbital Gears Ltd. Of Rhayader built and supplied the Motor Gearbox and Pump interface.
We went back about a year ago and installed a P.C. based Scada Software System to allow the rig to carry out, record and log the tests fully automatically.
Design and Supply of an Engine Test Rig update for Cummins Diesel
This job was completed about 18 months ago and involved the supply of a new Drive and Control System for an existing Diesel Engine test Rig. The original test rig was based on a ‘ David McClure ‘ Electrical Dynamometer Machine and the concept was that the drive acts as a line commutated inverter which loads the engine and feeds the power back into the mains.
Cummins wanted to upgrade the Rig, because they were finding the drive was becoming unreliable and they wanted to convert this cell to carry out emissions testing. The emissions work is very demanding, in that the requirements are to run the engine for a 20 minute cycle, simulating a vehicle being driven around a town, doing deliveries. Whilst this is going on samples of exhaust are collected from a dilution tunnel and tested.
A new Eurotherm Drives 590+ rated at 485 Kw was supplied along with a new PLC based control system, and for local control a Beijers Operator Screen. The new control system was also configured to work with the existing ‘ Prodogy ‘ computer based Scada System, for automatic control.
Pimbo Industrial Design Ltd
Aerospace, automotive
and electrical test rig
