• Selected problems of operation of machines with hydrostatic drive
  Kudźma Z., Palczak E., Rutański J., Stosiak M.
• Analytical assessment of volume capacity of hydraulic system of powered roof support leg
  Doległo L., Gil J., Stoiński K.
• Damages of welded joints in gob shield and safety of using of powered roof support
  Labus J., Markowicz J., Szweda S.
• Modelling and simulation of phenomena, which take place in powered-roof support
  Domagała Z.
• Newest trends in testing the interaction between rock mass and powered roof supports
  Smolnik G.
• Supply and control of operation of hydraulic drifter drill with use of LS system
  Marianowski J.
• Dust collecting equipment of wet type used in mining industry – disadvantages, advantages and development prospects
  Jedziniak M.
• Impact of dynamic actions on operational life of hoisting ropes in shaft hoists
  Małecki J., Tytko A., Wróbel T.

Selected problems of operation of machines with hydrostatic drive

Kudźma Z., Palczak E., Rutański J., Stosiak M.

Some problems of operation of machines with hydrostatic drive were presented in the paper. Some sources of vibrations and noise in operational machines were identified. The paper focused on hydraulic factors. Negative effects of vibrations were indicated. Use of damper of pressure pulsation was suggested as an effective method for reduction of reasons of excessive noise.

Analytical assessment of volume capacity of hydraulic system of powered roof support leg

Doległo L., Gil J., Stoiński K.

The Coal Company, JSC mostly exploits the seams threatened by bumping hazard. Usefulness of powered roof supports to bumping conditions is assessed on the basis of ability to absorb excessive stresses without support damage according to § 440 item 2 of the Decree of Minister of Economy as regards Occupational Safety (Journal of Laws No. 124, item 863, 2006). Capacity of hydraulic system of a leg is one of basic parameters, which are used in assessment of support. Analytical method, which was presented in the paper, enables assessment of operational liquid of a leg with use of numerical modeling based on ANSYS CFX software.

Damages of welded joints in gob shield and safety of using of powered roof support

Labus J., Markowicz J., Szweda S.

Damages of welded joints in a gob shield, which occurred during use of powered roof support, are the paper subject. Most frequent damages of welded joints in a gob shield of powered roof support were described on the basis of results of questionnaire inquiries as regards supports, which were selected for repair, that were carried out in longwall working and results of measurements of parameters, which characterize damages of welded joints. Impact of the damages on an effort of gob shield was analyzed. Size of damage of welded joint, which causes a permanent deformation of discussed support component, were determined. They were compared with a size of damage of welded joint in currently designed powered roof support, that could cause a permanent deformation of gob shield.

Modelling and simulation of phenomena, which take place in powered-roof support

Domagała Z.
A problem of simulation of dynamic phenomena in mining hydraulic support was presented in the paper. Structure of mathematical model, including simplifications, was described. On that basis a simulation model was created and tests, from which suitable conclusions were drawn, were carried out.

Newest trends in testing the interaction between rock mass and powered roof supports

Smolnik G.
Newest trend in world mining industry as regards selection of powered roof support is associated with use of so-called rock mass reaction curves. These curves are graphical presentation of relationship between load of support and convergence of working, what enables to determine, among others, support’s load bearing capacity to maintain required the convergence of working at given level.

Supply and control of operation of hydraulic drifter drill with use of LS system

Marianowski J.
An idea of rotary-and-percussion drilling was shortly presented and basic parameters, which determine optimal drilling speed, were specified in the paper. Operation of hydraulic system, which is based on supply by a pump of changeable capacity and control with the use of proportional distributors, was presented. Control of operational system of drilling jumbo based on supply by pumps of constant capacity and on supply by pumps of changeable capacity was described.

Dust collecting equipment of wet type used in mining industry – disadvantages, advantages and development prospects

Jedziniak M.
Dust collecting equipment of wet type, which is currently used during drivage of roadways by road-headers, was reviewed. Principle of operation of equipment, scope of its use and differences between each design were presented. Directions of development of equipment, especially as regards ensuring effective combination of dust with water, and purification of water removed from the equipment, were presented.

Impact of dynamic actions on operational life of hoisting ropes in shaft hoists

Małecki J., Tytko A., Wróbel T.
Steel ropes, especially hoisting ropes of mining shaft hoists, have limited life, which results from their fatigue strength. The paper authors suggest conducting of continuous measurement of forces in ropes of shaft hoists, with two hoisting ropes and single hoisting rope, to determine dynamics of loads of rope in the whole operational cycle of shaft hoist. Measurements of forces in a rope will enable to assess an impact of speed control system of hoisting machine and braking control on dynamics of loads. Recognition of dynamics will enable optimization of control system of hoisting machine drive to reduce dynamic overload in ropes at those stages of hoisting machine cycle of operation, in which change of operational speed is initiated. Decrease of this dynamics should have a positive impact on fatigue wear of ropes that appears in rope breaks.