A Comparative Study between L-Type and E-Type Primary Reducers

Nils Young, PE, Managing Director

 

Basic Design

 

E-Type Reducers L-Type Reducers
Type  Helical gearbox Helical gearbox
Torque indication Large 6” visual gauge indicating units of torque Large digital meter indicating units of torque
Torque operation In one direction In either forward (CW) or reverse (CCW)
Alarm & cutoff switches Yes Yes
Mechanical torque overload Protection Shear pin Shear pin
Optional 4-20ma torque trans signal Yes Yes
Variable speed option Yes. AC Inverter 10:1 Yes. AC Inverter. 10:1
Lubrication Semi-fluid grease Semi-fluid grease
Maintenance Change every 5 years Change every 5 years
Efficiency 95% 95%
Back drive Yes Yes
Reversing Yes Yes
Housing material of construction Carbon steel and painted  SS 304
Minimal safety factor 3.0 Yes Yes

 

Advantages of the L-Type over the E-Type

The DBS L-Type torque meter is a solid-state design, highly accurate, simple and reliable.  It uses a load cell to obtain the output load.  The E-Type is a mechanical design which measures the torque reaction of the primary reducer.  The E-Type gauge only works in one direction.  The L-Type torque meter works in any direction.  Torque indication could be useful when jogging the rakes lose from sludge.  

Unlike the E-Type, which allows the gearbox to swivel on a shaft and bearings, the L-Type primary gearbox is fixed.    

The L-Type is clean and very easy to service.  It has less parts than the E-type. There are only two major components in the torque meter, a meter and a load cell.  The components are easy to replace.  Basic tools are all that is required.  The E-Type torque gauge is a hydraulic assembly made with pressure components, fittings and tubing.  Leaks are possible and the procedure to repair is challenging since it requires eliminating air in the system. Unlike the E-Type, the L-Type eliminates an adapter that includes bearings, seals, bushings, torque arm linkage, and hydraulic reaction cylinder. 

Components are easier to replace. Cantilever loads applied by the weight of the gearbox and electric motor are not a design factor. The load cell housing of the L-Type has a much larger capacity to handle the lubricant expansion coming from the planetary gearbox than the E-Type.  A check breather, which is installed in the E-Type is not needed for the L-Type.

The torque meter enclosure material of the L-Type is stainless steel 304 as standard. It is available as an option with the E-Type.

L-Type is less susceptible to temperature variations than the E-Type.  

 

Advantages of the E-Type over the L-Type

Explosion proof requirement is not available in the L-Type. It is an available option on the E-Type. Power is required to operate the L-Type Torque Meter, whereas the E-Type Torque Gauge is mechanical and does not require power to operate.  

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Figure 1 - Model D104-GL3