Blake's Jake brake trial
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by Bryan Jarvis • Commercial Motor and Jacobs Europe have launched a user trial to determine the benefits of specifying a Jake engine brake. The 12-month programme involves a matched pair of Makes Chilled Distribution ERF EC14 6x2s.
Both twin-steer tractors have sleeper cabs, 340hp 14-litre Cummins engines, Eaton Twin Splitter gearboxes and Rockwell axles. One is equipped with a three-stage Jake brake, operated via the footbrake.
The trial is being supported by ERF via its Strathclyde dealership and contract maintenance centre at Middlewich. The artics were supplied by S Jones and Son but ERE Strathclyde is providing fleet cover under a maintenance and repair contract.
Blakes has 75 ERFs based at its Scottish depot, including the two vehicles in the Jake brake trial. Ten more are used exclusively by its continental business arm. The test vehicles are both 14 months old: the Jake 430-equipped ERF (J60BCD) has over 230,000km on the clock; the control vehicle (J50BCD), which has a standard VPS exhaust brake, has covered 225,000km.
They pull 13.6m standard tri-axle reefers from Blake's Hartshill site down the same motorway route between Glasgow and the Midlands.
Their drivers switch around between these and other 3+3 rigs but all are fully trained in the use of the Jake and its perceived benefits. Before the evaluation programme both trucks in the Jake test had their braking systems overhauled by ERF Strathclyde. in-cab computers. IL.
The Gray & Adams reefer trailers are maintained by Blakes and operational restraints prevent the trial being extended to tractor/trailer braking compatibility.
To gather data for the trial Leafield AVM fitted both trucks with Vemis onboard computer and electronic monitoring equipment. Sensors on the footbrake, VPS exhaust brake and Jake brake provide information which is downloaded for analysis.
At the heart of the trial is a breakdown on the power and duration of every brake application, the distance covered between pedal movements and the amount of "harsh" braking (defined by ERF as deceleration beyond 8mph (13km/h) per second.
A precise count is kept of the number of Jake applications, which are broken down into light, moderate and heavy usage. Each artic descends Beattock and Shap twice a day so the amount of engine overspeeding highlighted during the programme will also be of great interest.
With such a mass of detail available, the trial will compare rates of wear, to brake-related and driveline components. It should help Blakes, or other operators, to decide on the value of forking out £1,450 for a Jake brake.
7 CM will report on the trial at the mid-way stage. The conclusion will be in August 1996.