The increased durability of the suspension system and reduction of shock to the overall machine has already directly translated into lower maintenance costs, reduced downtime, increased equipment life, and significantly greater operator productivity.

“At 2000-plus operating hours,” points out Toole, “the new gas strut suspension has been performing very well. There have been no structural failures on the frame or suspension. Maintenance has been zero, and there have been no oil or nitrogen leaks. Importantly, the operators like the ride. In fact, the machine operators are the best testimonials for the suspension. A big key to the nitrogen suspension is the fact that it is strictly nitrogen. It has proven to provide the fastest reaction time, because there is no oil to displace, as with other systems.”

BTI’s QS45 Scaler

The QS series of mining scalers are showpieces of hydraulics. Their design — chock full of fluid power technology — eliminates the “rock ‘n roll” high maintenance issues that are common with other designs. In addition to the balance and stability of the unit’s gas strut suspension system, the QS45 features the first vibrating pick scaling head. To eliminate the problems associated with mechanical scaling, BTI has combined the action of a pry-bar, pick, and breaker into a single attachment that rotates 360°. Results are production increases of up to 50%, extremely low operating costs, reduced operator fatigue and reduced stress to the carrier.

To an operator, control of the scalers is similar to that of an excavator. The machine features hydraulic pilot controls (joysticks) and two foot pedals for brake and speed control.

Driving, swing and boom, suspension, and vibratory pick are all hydraulic. There are two main loadsensing (auto engine/hydraulic match to demand) pumps (variable displacement/axial-piston) with maximum flow of 2 57.9 gpm (115.8 gpm). Load sensing directional valves are hydraulically pilot operated by the joysticks. A separate pressure compensated pump circuit, totally independent of the two load-sensing pumps, is used for steering and braking. A 66-gal capacity reservoir is standard.

System operating pressures are as follows:

Main circuit 5000 psi
Hydrostatic propel circuit 5000 psi
Swing circuit 4270 psi
VP pick circuit 2400 psi
Boom hoist circuit 5000 psi
Boom extension circuit 3000 psi
Boom rotation circuit 3000 psi
Tilt circuit 5000 psi
Steering and brake circuit 3000 psi

The QS45 features a 45-ft. reach triangular telescopic boom that incorporates three 94,000-psi yield strength tubes, a massive counterweight and highcapacity 269-gal fuel tank. With all of the above combined with the square geometry of the chassis and the 360° continuous swing capability, the unit works with uniform stability in any direction without stabilizers.

In addition to the three-point monitoring, the ergonomically designed operator cab has an 85-dB noise level rating.

As far as electronic controls, again they are designed to mimic that of an excavator, with the exception of the vibratory pick. These smart controls prioritize the hydraulic distribution of power. There is a monitor system, complete machine system tracking, and diagnostics capability — downloadable to a PC.


Generally, scalers are expected to have a four- to six-year life, and seven years of use is considered good. With the accumulator/cylinder gas strut suspension, BTI promotes the following overall benefits: • Longer suspension life before major overhaul. Rubber air bags can be damaged by debris during vehicle operations. The gas strut suspension has a life expectancy several times greater than possible with air bag and spring suspensions. This directly translates to lower maintenance costs and less downtime. • Significant reliability over rubber air bag suspension systems. With an entirely rubber surface, air bags have a much greater chance of gas permeation through the rubber. The steel cylinder acts as a barrier in the QS45 gas strut. It is also combined with a virtually leak-proof seal to ensure that the gas pre-charge is always maintained. • Significantly lower owning and operational cost. Due to less wear and tear, the QS45 scaler is costing 25% less per hour to operate than traditional scalers with air bag suspensions. Fuel consumption is just over 4 gal/hr vs. 8 to 11 gal/hr for competitive units. • Better overall reliability. With the combination of unit balance and stability, reliability for the QS45 is currently running at 90%, comparing favorably with competitive scalers. • 50% productivity improvement due to lower vibration and noise levels and less operator fatigue, and • A smaller, more compact machine. Because the suspension is more compact, the overall height of the unit decreased. This solved a big issue for transportation — both on the highway and when entering the workplace.

In the QS45 suspension, the cylinder OD is 7.5-in. with a 30-in. length when extended. This allows for a 3-in. clearance from the top of the strut to the undercarriage. Cylinder length was limited due to space constraints, so a remote auxiliary gas bottle was used to ensure sufficient nitrogen gas capacity for the vehicle’s initial loading.