Système de contrôle de la pression des pneus (TPCS)
Les systèmes de contrôle de pression (TPCS) ou de gonflement central des pneus (CTI) deviennent de plus en plus populaires dans les opérations forestières canadiennnes comme moyen d'accroître la mobilité des camions grumiers et de prolonger la saison de transport. Cependant, il existe très peu d'information quant à leurs coûts de possession et de fonctionnement. FERIC a observé les systèmes TPCS Redline-Eltek et TPCS Eaton durant une période de trois ans. L'étude portait sur 24 camions grumiers de configurations variées, localisés dans six endroits différents de l'ouest du Canada. Le rapport présente les coûts de possession et de fonctionnement des systèms TPCS pour ces 24 camions et décrit comment le taux d'utilisation du camion affecte les coûts de possession du TPCS et du camion.
La pression nominale au sol est un critère important utilisé pour prévoir les effets du poids et de la configuration d’une machine sur les sols forestiers durant les activités de récolte. Le présent rapport traite du concept de pression nominale au sol, de la façon dont il s’applique à différents types de machines ainsi que l’effet des diverses configurations des machines.
This report evaluates a new fluctuating pressure treating process, with a small pressure variation, that could be easily implemented into a treating plant with a control value. Coastal western hemlock being a relatively difficult species to impregnate was chosen as a suitable test species. Incised and unincised hemlock was used to relate to present industry practices.
Elimination of saw kerf through the compression slicing process has initiated research into the optimization of the compression slicing parameters. Five of these parameters have been selected for study in the 1979-1980 federal fiscal year, through a contract given to Forintek Canada Corp. by Environment Canada. These parameters are the following: 1) Find an alternative to tires or pads for lateral pressuriza tion, 2) Study knife profile to reduce checking damage, 3) Study knife tensioning to reduce checking damage, 4) Study methods of reducing knife friction, 5) Study the dustribution of stresses in the knife when tensioning and slicing. Following is a detailed description of the work done during the 1979-1980 federal fiscal year on each of these compression slicing parameters.
The recently revived interest in borate treatment for the production of termite-resistant lumber has led to the need for more rapid treatment processes. Pre-steaming prior to pressure treatment was known to have a number of potential benefits in terms of improved permeability, moisture distribution and vacuum. This process was therefore tried on western hemlock and amabilis fir Dodai (baby squares) in an attempt to achieve through-treatment without a diffusion period after pressure treatment. Western hemlock pre-steamed to a core temperature of 65 degrees C received a 25% increase in solution uptake and a 41% increase in mean heartwood penetration using a two hour pressure period. Amabilis fir pre-steamed to a core temperature of 90 degrees C received a 40% increase in solution uptake but no measurable increase in heartwood penetration. This was because penetration measured from the heartwood face was virtually complete in the amabilis fir treated without pre-steaming. Pre-steaming hemlock and amabilis fir Dodai appears to be a very effective means of improving uptake during pressure treatment. Further optimisation of this process is still possible.
The recent interest in borate treatment for the production of termite-resistant lumber has led to the need for improved treatment processes. Pre-steaming prior to pressure treatment was known to have a number of potential benefits in terms of improved permeability, moisture distribution and effectiveness of the vacuum. This process was therefore tried on western hemlock dodai (105 mm squares) in an attempt to achieve 80% cross sectional penetration with a minimal diffusion period after pressure treatment. Western hemlock pre-steamed to a core temperature of 82 degrees C in four hours took up almost double the amount of treating solution of end-matched unsteamed samples. There was an improvement in mean heartwood penetration of 45% immediately after treatment and a 134% increase in penetration after one week storage. This was not entirely due to diffusion within the wood but to mass flow of treating solution continuing after the end of the pressure process. After one week storage 64% of samples had 80% of the cross section penetrated. Reducing the vacuum time from 30 minutes to zero had a detrimental effect on penetration. Increasing time under vacuum to 60 minutes provided no beneficial effect. Pre-steaming of hemlock dodai appears to be a very effective means of improving uptake during pressure treatment.