1. What is a compressor?

The compressor is basically an air pump, which takes air and pumps it into a small tank. When increasing pressure more air is crammed into the same tank. This compressed air is used to power HUR machines. When you press the + (plus) button a valve opens and air flows from the compressor tank into machine. Pressing the – (minus) button air is freed out of the machine and resistance is reduced. The amount of resistance depends on how much air is added to machine.

2. Can several machines be connected to the same compressor?

Yes. However, the number of machines connected to the same compressor depends on the usage of machines. We recommend different kind of compressors depending on that usage.

3. What kind of service is needed?

Machines themselves need very little service. We recommend to wipe the upholstery once a day. This is also a comfort issue. If you have an old model of compressor you also need to empty the compressor tank once a week. This is because air humidity causes water condensation in the tank. On newer compressor models emptying is done automatically into a plastic bottle and you only have to empty the bottle as it fills up. We also recommend that you lubricate the cylinders once a year. This can be done without tools in a few minutes.

4. Can I install machines myself?

In most cases Yes. There are a few things to take care of, though. As the machines work on air pressure they must be connected to a compressor. Several machines can be connected to the same compressor and a small tube does this. You install a main tube, usually along the wall, and at each machine you attach a T connector to the line. All connectors are “push in” so they will automatically attach to tube. The only thing you need to do is to cut the tube at the appropriate positions. You should also take care of not to get sand, dirt or foreign particles into the network as these might damage valves. This can easily be taken care of by turning on the compressor once before you connect the machines to the network. Turning on the compressor will blow the network clean from any foreign particles.

5. Can I service machines myself?

Yes. One of the key design criteria on HUR machines has been to make service as simple as possible. There is not much service needed. Normal maintenance includes wiping the upholstery and lubricating the piston rods of the cylinders once a year. This can be done without tools.

6. What can go wrong?

Actually very little. HUR machines have no wires, cams or cables. All moving joints are with ball bearings. Cushion rollers have been lubricated upon leaving the factory, but in a few years in dry air they might dry out and start squeaking. The remedy is to lubricate them.

7. What is reliability of the cylinders?

We actually don’t know. The first machines that we made in 1989 are still in daily use. The resistance cylinders we use have been tested for 10 million cycles without any signs of wear or tear. These are all industrial grade heavy duty components which are made to last for years in harsh conditions. Fitness usage is after all a rather light and easy environment.

8. Where can I get spare parts?

Naturally from us directly or from your nearest HUR dealer. However, HUR machines use only industrial standard valves and cylinders, so you can practically get replacement parts from any pneumatic supplier. If in some distant future your HUR machine breaks down and you cannot reach us, bring the damaged part to the nearest pneumatic shop. They will definitely be able to find you a similar replacement. HUR is also the only supplier of pneumatic exercise machines to use only standard components. This might be more expensive but it guarantees the availability of reasonably priced spare parts anywhere in the world for the foreseeable future.

9. What is Natural Transmission?

Natural Transmission resistance mechanism is a system that was developed at the University of Technology in Helsinki in the 1980s. Simply put, Natural Transmission replaces all cams and cables of exercise machines with a transmission system that mimics the muscle function itself. This has 2 benefits. First, it gets closer to how a muscle actually works which means a higher training effect, and secondly, it also increases reliability. In Natural Transmission all moving joints are with ball bearings. This means that wires and cables, which are the items most likely to break down on weight stack machines, have been totally eliminated.

10. Are your machines intended for muscle toning or for strength training?

Both. It is up to you! The unique feature of HUR machines is that you can increase the velocity in order to burn more energy. If you like to tone your muscles, simply use low workloads and fast movements. Whereas for building muscle size you use higher resistance, slower velocity and fewer repetitions.

11. What is the difference between hydraulic and pneumatic machines?

The difference is that hydraulic machines use oil and pneumatic machines use air pressure. In addition to this there are fundamental differences from a biomechanical and physiological point of view. Hydraulic machines only work concentrically and have no eccentric resistance. They always only restrict the movement whereas in nature the muscles always work both ways. In nature you lift a weight concentrically and you lower it down eccentrically. The case of hydraulic machines is akin to first lifting a weight up and then pushing it down: there is no resistance like that in nature. Pneumatic machines have both concentric and eccentric resistance.

12. What is inertia ?

Inertia is a term used in physics to describe movement energy. If you like to lift a weight you need to exert the same force as the force of gravity acting on the weight. However, this is not enough. You also have to apply an additional force to get the weight moving. When you want to stop the weight a force in the opposite direction is required to slow the weight down. Inertia is the force, which opposes a change of movement velocity. Things like to remain the way they are. You need forces both to accelerate things and to slow things down. These forces are inertia.

In a training context these inertial forces also cause the resistance curves of weight stack machines to change depending on the way the movements is performed. There is always an additional force required in order to accelerate the weights, which makes the resistance heavier at the beginning of the movement, and at the end of the movement the same inertial effects make the movement lighter. As a result the resistance curves of weight stack machines can never really accommodate to the force curves of the muscles since they change depending on how the movements are performed.

13. What about the durability of pneumatic machines compared to weight stack equipment? 

Durability is of course something that is dependent on many variables and not merely the principle of how resistance is produced. There are numerous weight stack machine manufacturers, and each machine should be assessed based on its individual properties. The first machines manufactured by HUR in 1988 are still in daily use today; the cushions have been replaced several times but the frames and power trains, including resistance cylinders, are original. HUR machines rely on pneumatic components that meet the ISO and VDMA industry standards. These are the exact same components used in industrial facilities, where mechanical failures can cost millions (for example, within the paper industry)